OBJECTIVETo evaluate the correlation of CDK4 protein expression in the cytoplasm with the clinicopathologic features and prognosis of lung cancer.

METHODSImmunohistochemistry was employed to examine CDK4 protein expression in the cytoplasm of lung cancer samples, using normal lung tissue samples as control. The correlation of cytoplasmic CDK4 protein expression with the clinicopathologic parameters and prognosis of lung cancer patients was analyzed.

RESULTSNo significant difference was found in cytoplasmic CDK4 protein expression levels between lung cancer and normal lung tissues (P=1.000). In the lung cancer tissues, however, an increased cytoplasmic expression of CDK4 was positively correlated with the clinical stages and lymph node metastasis. Prognostic analysis showed that the patients with an increased cytoplasmic CDK4 expression had a markedly shorter overall survival than those with a low cytoplasmic CDK4 expression. Multivariate analysis suggested that the level of cytoplasmic CDK4 expression was an independent prognostic indicator for the survival of patients with lung cancer (P<0.001).

CONCLUSIONOverexpression of CDK4 protein in the cytoplasm may promote the carcinogenesis of lung cancer and can be an unfavorable prognostic factor for the survival of lung cancer patients.