Expression of CDK5/p35 in resected patients with non-small cell lung cancer: relation to prognosis

Overall outcome of those patients with non-small cell lung cancer (NSCLC) remains poor. Recently, several studies demonstrated that cyclin-dependent kinase-5 (CDK5) activity with its specific activator protein p35 was important for spontaneous metastasis in various types of carcinomas. Our objective was to explore the expression of CDK5 and its prognostic indicator in patients with NSCLC. Immunofluorescent staining was used to detect the expression of CDK5/p35 in the lung tissue of 95 patients with NSCLC and 20 patients with benign pulmonary disease. The correlation between the expression of CDK5/p35 and clinicopathologic features of patients with NSCLC was investigated. The 5-year overall survival of patients with tumors expressing different levels of CDK5/p35 was evaluated by the Kaplan-Meier method. Positive expressions of CDK5/p35 were detected in the tumor cells in 66 samples (69.5%) of the 95 patients with NSCLC. Although no remarkable correlation between CDK5/p35 expression and age at the time of surgery, gender, and histopathologic type, there were significant differences between CDK5/p35 expression and degree of differentiation, pathological stage and lymph node metastasis in patients with NSCLC. In addition, we demonstrated that median survival for patients with and without CDK5/p35 expression was 24 and 58 months, respectively, and 5-year overall survival rate 25.8 and 48.3%, respectively (P<0.05). Patients with lung cancer with a positive CDK5/p35 expression had a poorer prognosis than those with a negative CDK5/p35 expression. Based on our results, CDK5/p35 may represent a biomarker for prognosis in patients with NSCLC.