Expression of autophagy and ER stress-related proteins in primary salivary adenoid cystic carcinoma.

Autophagy is the endogenous cellular pathway that facilitates cellular survival by maintaining energy homeostasis and macromolecular synthesis during cellular stress and nutrient deprivation. Endoplasmic reticulum (ER) stress is the process in which disruption of these physiological functions leads to an accumulation of unfolded proteins and induces the unfolded protein response (UPR). ER stress and autophagy are involved in human cancer. We investigated the expression of autophagic proteins (LC3 and beclin 1) and ER stress-related protein (GRP78) in head and neck adenoid cystic carcinoma tissue. Tissue samples from 79 cases of head and neck adenoid cystic carcinoma tissue were utilized for immunohistochemistry. LC3 expression was significantly correlated with lymph node involvement (P=.016) and TNM (P=.021). Beclin 1 expression was significantly correlated with the histological growth pattern (P=.002), the histological grade (P=.000), and longer survival (P=.000). GRP78 expression was significantly correlated with the histological growth pattern (P=.019), the histological grade (P=.019), and longer survival (P=.001). LC3 expression was positively correlated with beclin 1 expression (P=.000); LC3 and beclin 1 expressions were positively correlated with GRP78 expression respectively (P=.035) (P=.008). Our study describes the expression of LC3, beclin 1, and GRP78 in adenoid cystic carcinoma and its relationship with clinicopathologic factors and overall survival. These results suggest that LC3, beclin 1, and GRP78 may play an important role in the tumorigenesis of adenoid cystic carcinoma, and that beclin 1 and GRP78 may serve as new prognostic indicators for the outcome of patients with adenoid cystic carcinoma.