Nuclear expression of CDK4 correlates with disease progression and poor prognosis in human nasopharyngeal carcinoma.

Aims The purpose of this study was to examine the correlation between nuclear expression of cyclin-dependent kinase 4 (CDK4) and clinicopathological data in nasopharyngeal carcinoma (NPC), including patient survival. Methods and results Using real-time PCR and immunohistochemistry, the expression of CDK4 was examined in NPC and nasopharyngeal (NP) tissues. We observed that mRNA expression of CDK4 was elevated significantly in NPC tissues compared to NP tissues. Further, we found that CDK4 protein was expressed in both the nucleus and cytoplasm. Nuclear expression of CDK4 was correlated positively with clinical stage (P = 0.048), but not associated with other clinical features. Patients with tumours showing nuclear expression of CDK4 had poorer overall survival rates than those without nuclear tumour expression of CDK4. Nuclear expression of CDK4 was associated inversely with survival time for NPC patients in stages T1–2, stages N2–3 and clinical stages III–IV, and after treatment with radiotherapy or chemotherapy. Nuclear expression of CDK4 was an independent and unfavourable prognostic factor for patients with NPC. Conclusions Our findings suggest that nuclear expression of CDK4 is a potential marker for the progression and poor prognosis of NPC.