Interleukin-13 receptor alpha 2 as a marker of poorer prognosis in high-grade astrocytomas.

BACKGROUND: Interleukin-13 receptor alpha 2 (IL13R alpha 2) is considered a prognostic marker for gliomas according to the World Health Organization (WHO) grade. However, the expression levels of the marker vary from case to case, even within the same grade. We investigated whether IL13R alpha 2 could serve as a predictor of poorer prognosis in gliomas. METHODS: mRNA expression of IL13R alpha 2 was measured using real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR) in 52 formalin-fixed paraffin-embedded glioma samples (4 pilocytic astrocytomas, 9 diffuse astrocytomas, 12 anaplastic astrocytomas, and 27 glioblastomas, grade IV). The expression levels were compared with regard to WHO grade, MIB-1 index, patient's age, and overall survival. RESULTS: Real time qRT-PCR showed that IL13R alpha 2 is expressed in a subset of cases with a progressive increase from low-to high-grade astrocytomas (HGAs). The expression had a significant positive correlation with the MIB-1 index and advanced patient age at diagnosis. The overall survival (OS) of patients who had HGAs with higher levels of IL13R alpha 2 expression was significantly lower than the OS of those with HGAs with lower levels of IL13R alpha 2. In the 39 HGA cases studied, the median survival benefit in the lower expression group was 167.4 months. The median OS (mOS) in HGA group with lower IL13R alpha 2 expression was 186.4 months, while the mOS in the group with higher IL13R alpha 2 expression was 18.6 months (P=0.033). The hazard ratio, adjusted by fitting the Cox proportional hazard models for the mOS in the HGAs with higher IL13R alpha 2 levels and the HGGs with lower IL13R alpha 2 levels, was 5.97 (95% CI: 1.76 to 20.32). CONCLUSIONS: The results showed that IL13R alpha 2 may be used as a marker of poorer prognosis in HGAs, even among tumors of the same grade.