Pim-1 proto-oncogene, serine/threonine kinase (PIM-1) phosphorylates a series of 
substrates to exert its oncogenic function in numerous malignancies. The present 
study investigated the clinical significance of the PIM-1 protein, apoptosis 
status and apoptosis-associated proteins, including forkhead box O3a (FOXO3a), B 
cell lymphoma-2 (BCL-2) and BCL-2-associted agonist of cell death (BAD), were 
investigated in salivary gland adenoid cystic carcinoma (ACC) tissues. PIM-1 
expression levels in 4 pairs of ACC tissues and corresponding normal salivary 
gland tissues were determined by western blot analysis. PIM-1, FOXO3a, BAD and 
BCL-2 expression levels in 60 ACC tissues were evaluated by immunohistochemistry 
(IHC). A terminal deoxynucleotidyl-transferase-mediated dUTP nick end labeling 
assay was performed to detect the apoptosis status of ACC tissues. PIM-1 was 
revealed to be highly expressed in ACC tissues compared with adjacent normal 
tissues. IHC staining results demonstrated high expression ratios of PIM-1, 
FOXO3a, BCL-2 and BAD [33.33% (20/60), 51.67% (31/60), 51.67% (31/60) and 55% 
(33/60)], respectively, and significant correlations between the expression of 
PIM-1 and FOXO3a and BCL-2 (P<0.05). Apoptotic rates were significantly 
associated with PIM-1, FOXO3a, BCL-2 and BAD expression levels (P<0.05). PIM-1 
expression levels were significantly associated with tumor size, lymph node 
involvement, nerve invasion, distant metastasis and weakly associated with tumor 
node metastasis stage. Kaplan-Meier survival curves revealed that PIM-1 
expression level was significantly associated with disease-free survival of 
patients with ACC (P=0.009). Cox regression multivariate analysis results 
revealed that histotype, distant metastasis and apoptotic rate were independent 
prognosis factors for ACC. Assessment of PIM-1 may be useful in investigating 
the malignant behaviors of ACC and predicting the outcome of patients with ACC.