Altered capicua transcriptional repressor gene expression exhibits distinct prognostic value for isocitrate dehydrogenase-mutant oligodendroglial tumors

To evaluate the prognostic significance of the altered expression of capicua transcriptional repressor (CIC) in isocitrate dehydrogenase (IDH)-mutant oligodendroglial tumors, a cohort of 54 IDH-mutant oligodendroglial tumors (designated as the Xijing cohort) were examined by immunohistochemistry (IHC), and two public expression data sets from The Cancer Genome Atlas (TCGA; n=265) and the Gene Expression Omnibus (GEO; n=45) were analyzed in the present study. The prognostic value was evaluated by survival analysis and Cox hazards models. Overall survival (OS) was investigated with Kaplan-Meier curves and log-rank tests. Gene set enrichment analysis (GSEA) was also performed to characterize the functional profiles of each subgroup. It was revealed that in IDH-mutant, 1p/19q co-deleted oligodendroglial tumors, higher CIC expression (at mRNA and protein levels) was associated with a more favorable OS time (log-rank P-values: TCGA, P=0.034; GEO, P=0.012; Xijing cohort, P=0.029). By contrast, among IDH-mutant, 1p/19q intact tumors, higher CIC expression was associated with poorer OS time (log-rank P-values: TCGA, P=0.007; GEO, P=0.017; Xijing cohort, P=0.012). To the best of our knowledge, this is the first study demonstrating the distinct prognostic value of altered CIC expression with regard to the 1p/19q status among IDH-mutant oligodendroglial tumors. The dual roles of CIC may be influenced by its transcriptional regulatory activity and the consequent functional profiles. Additionally, a simple risk classification scheme based on CIC expression alone is proposed for the optimal prediction of prognosis in patients with oligodendroglial tumors.