Integrated analysis identified genes associated with a favorable prognosis in oligodendrogliomas

Oligodendrogliomas (ODs) are the second most common malignant brain tumor and exhibit characteristic co‐deletion of chromosomal arms 1p and 19q (co‐deletion 1p/19q), which is associated with down‐regulation of tumor suppressors. However, co‐deletion 1p/19q indicates a favorable prognosis that cannot be explained by the down‐regulation of tumor suppressors. In the present study, we determined that co‐deletion 1p/19q was associated with reduced Ki‐67 protein level based on analysis of 354 ODs. To identify genes associated with reduced Ki‐67 and a favorable prognosis of codeletion 1p/19q, we analyzed 96 ODs with RNA‐sequencing and 136 ODs and 4 normal brain tissue samples with RNA microarrays. We thus identified seven genes within chromosomal arms 1p/19q with significantly reduced expression in samples with co‐deletion of 1p/19q compared to samples with intact 1p/19q. A significant positive correlation was observed between these candidate genes and Ki‐67 expression based on analysis of mRNA expression in 305 gliomas and 5 normal brain tissue samples. Survival analysis confirmed the prognostic value of these candidate genes. This finding suggests that these genes within chromosomal arms 1p/19q are associated with low Ki‐67 and a favorable prognosis in ODs with co‐deletion 1p/19q and provides novel therapeutic targets. © 2015 Wiley Periodicals, Inc.