Association between high expression of phosphorylated Akt and mammalian target of rapamycin and improved survival in salivary gland adenoid cystic carcinoma.

BACKGROUND: Previous genomic studies revealed phosphotidylinositol-3-kinase (PI3K)/Akt pathway mutation in human salivary gland adenoid cystic carcinoma (ACC). No validation of its prognostic value has been reported. METHODS: P-Akt, pan-Akt, phosphorylated-mammalian target of rapamycin (p-mTOR), PI3K, and insulin-like growth factor-1 receptor beta (IGF-1Rß) were detected on 120 salivary gland ACC/adjacent salivary gland pairs immunohistochemically and were correlated with clinicopathological data. RESULTS: Expression of cytoplasmic and nuclear p-Akt, cytoplasmic p-mTOR, nuclear pan-Akt, and nuclear IGF-1Rß were higher in ACC than in adjacent salivary glands. P-Akt, p-mTOR, PI3K, and IGF-1Rß expression were correlated with one another in both cytoplasm and nucleus. Low p-mTOR expression in both subcellular compartments was associated with locoregional recurrence, poor disease-free survival (DFS), and overall survival (OS). Low nuclear p-Akt (Ser473) and p-mTOR expression were independent predictors for poor OS and DFS, respectively. CONCLUSION: High level of Akt/mTOR activation in ACC is correlated with a significantly improved survival. P-mTOR and nuclear p-Akt are prognostic biomarkers of salivary gland ACC. © 2017 Wiley Periodicals, Inc. Head Neck 39: 1145-1154, 2017.