Aberrant expression of CDK8 regulates the malignant phenotype and associated with poor prognosis in human laryngeal squamous cell carcinoma

CDK8, a member of the transcriptional subtype of the cyclin-dependent kinases (CDKs) family, shows remarkable cancer tissue specific expression profile and rather more selective contribution to the regulation of gene expression levels involved in some signaling pathways. However, the effect of CDK8 on the malignant phenotype of human laryngeal squamous cell carcinoma (LSCC) cells and the potential molecular mechanisms remain unclear. In the present study, we evaluated the expression levels of CDK8 by quantitative real-time reverse-transcriptase polymerase chain reaction (qRT-PCR) and immunohistochemistry in tissue samples of 60 LSCC patients. Then we analyzed and correlated the results with clinicopathological features. We demonstrated that CDK8 was significantly overexpressed in LSCC tissues compared with normal controls, and this overexpression was correlated with lymph node metastasis and advanced clinical stages. Kaplan-Meier analysis showed that high expression levels of CDK8 miRNA significantly correlated with short OS survival. In addition, down-regulation of CDK8 using small interfering RNA(siRNA) reduced the proliferation and migration of LSCC in vitro. To explore the potential mechanism, we investigated the effect of CDK8 on Wnt signaling pathway and found that CDK8 was involved in the EMT progress by regulating beta-catenin of the Wnt signaling. In summary, our data suggest for the first time that CDK8 appears to contribute to the malignant mechanism of LSCC and may represent a significant prognostic marker for LSCC patients.