Expression of BNIP3 and its correlations to hypoxia-induced autophagy and clinicopathological features in salivary adenoid cystic carcinoma.

Abstract

The expression of Bcl-2/adenovirus E1B 19 kDa-interacting protein3 (BNIP3) has been explored in many human malignancies, but not in adenoid cystic carcinoma (ACC). This study investigated the clinical significance of expression of BNIP3 in ACC tissues and cells and elucidated its correlations to hypoxia-induced autophagy. Immunohistochemical and immunofluorescence staining were used to explore BNIP3, HIF-1α and LC3 expression. BNIP3 was positively expressed in 41 cases (63.1%), and was significantly correlated with histological grade (P= 0.001). HIF-1α was positively expressed in 52 cases (80.0%) and was significantly correlated with TNM stage (P= 0.023) and histological grade (P= 0.024). LC3 was positively expressed in 37 cases (56.9%) and was significantly correlated with TNM stage (P= 0.019). The expression of BNIP3 was correlated with HIF-1α expression (P= 0.011). The overall survival in the negative BNIP3 expression group tended to be better than in the positive BNIP3 expression (P= 0.011). In vitro experiment, BNIP3 immunofluorescence staining was detected in cells treated with CoCl2 (for hypoxic condition). The data indicated that BNIP3 plays a vital role in the tumorigenesis of adenoid cystic carcinoma and could be a new target for gene therapy of adenoid cystic carcinoma.