Insights into the clinical value of cyclin-dependent kinase 5 in glioma: a retrospective study

BACKGROUND Previous studies suggested that expression of cyclin-dependent kinase 5 (CDK5) may promote the migration and invasion of human glioma cells. In this study, we aimed to evaluate the clinical value of CDK5 in different grades of glioma in relation to Ki-67 labeling index (LI). METHODS We firstly assessed by immunohistochemistry the expression of CDK5 in 152 glioma tissues and 16 normal brain tissues and further explored the relationship between CDK5 expression and other clinical features. RESULTS The positive ratio of CDK5 in gliomas (57.2%) was higher than that in normal brain tissues (12.5%, P=0.001). Difference of CDK5 expression among four World Health Organization (WHO) grades was statistically significant (P=0.001). The significant differences of CDK5 expression were also observed between WHO I glioma (34.8%) and WHO III glioma (62.5%), as well as WHO IV glioma (82.8%; P=0.026, P<0.001, respectively). Furthermore, Spearman's rank correlation confirmed that CDK5 was positively correlated with the pathological grade of glioma (r=0.831, P<0.001). The CDK5 expression was also positively correlated with Ki-67 LI (r=0.347, P<0.001). CONCLUSIONS The current result suggests that CDK5 may play an essential role in the tumorigenesis and aggressiveness of gliomas.