Cyclin-dependent kinase 8 is an independent prognosticator in uterine leiomyosarcoma

Cyclin-dependent kinase 8 (CDK8) is associated with the transcriptional mediator complex and regulates several transcription factors implicated in cancer. CDK8 expression is a poor prognostic marker in colon and breast cancer by immunohistochemistry. However, somatic mutations in exon 2 of the RNA polymerase II transcriptional mediator subunit MED12 occur in 7-30% of cases of uterine leiomyosarcoma (ULMS), suggesting that these alterations contribute to tumorigenesis. Public genomic mutation data of 80 patients with ULMS were used for MED12 and CDK8 mutation analysis. The expression of MED12, CDK8 and β-catenin was evaluated by immunohistochemistry in our cohort of 60 patients with ULMS, in addition with MED12 mutation status and survival stage. Univariate analysis was performed using the log-rank test, and Cox regression was used to identify independent prognostic factors. Multivariate Cox regression analysis revealed that advanced stage (p < 0.0001) and high CDK8 expression (p = 0.0014) were independent predictors of poor prognosis. MED12 mutation status was not significantly associated with CDK8 expression (p = 0.6873) and DSS (p = 0.8075). In conclusion, our data suggest that CDK8 expression may identify a subset of ULMS patients with a poor prognosis.