Protein Kinase D1 Is Increased in Tumor Tissue, Correlates With Advanced Tumor Features and Worse Prognosis of Non-Small Cell Lung Cancer

OBJECTIVE: This study aimed to assess protein kinase D1 expression and its association with tumor characteristics as well as prognosis in patients with non-small cell lung cancer. METHODS: Protein kinase D1 expression in tumor tissues and adjacent tissues from 172 patients with non-small cell lung cancer who underwent surgical resection were analyzed by immunohistochemical staining. Based on the total immunohistochemical score, protein kinase D1 expression was classified as protein kinase D1 high expression (further divided into protein kinase D1 high(+++), protein kinase D1 high(++), and protein kinase D1 high(+) expressions) and protein kinase D1 low expression. Clinical characteristics of patients with non-small cell lung cancer were acquired from the database. Accumulating disease-free survival and overall survival were calculated based on patients’ relapse/survival status. RESULTS: Protein kinase D1 expression was increased in tumor tissues compared to adjacent tissues (P < .001). Tumor protein kinase D1 high expression correlated with poorer pathological differentiation (P = .041), increased tumor size (P = .003), the presence of lymph node metastasis (P = .001), and elevated tumor, nodes and metastases stage (P < .001). Besides, both accumulating disease-free survival and overall survival were decreased in patients with tumor protein kinase D1 high expression compared to patients with tumor protein kinase D1 low expression (P = .010 for disease-free survival and P = 0.005 for overall survival). Moreover, they were lowest in patients with tumor protein kinase D1 high(+++) expression, followed by patients with tumor protein kinase D1 high(++) expression, then patients with tumor protein kinase D1 high(+) expression, and highest in patients with tumor protein kinase D1 low expression (P < .001 for disease-free survival and P = .001 for overall survival). Notably, higher tumor protein kinase D1 expression was an independent predictive factor for decreased disease-free survival (P = .001) and overall survival (P = .004). CONCLUSIONS: Protein kinase D1 might be a potential marker to identify patients with non-small cell lung cancer with worse tumor features and prognosis.