Peroxiredoxins and their expression in ependymomas.

Aims: Peroxiredoxins I-VI (Prxs) have recently been shown to have a role in the tumorigenesis of astrocytic brain tumours. In some tumour types they are associated with Nrf2 (transcription factor NF-E2-related factor), a sensor of oxidative stress, and DJ-1 (also known as PARK7), a protein known to stabilise Nrf2.

Methods: We investigated the immunohistochemical expression of Prxs I-VI, Nrf2 and DJ-1 in a total of 76 ependymomas and their relationship with clinicopathological features of these tumours.

Results: There was a significant expression of all Prxs except Prx IV in the ependymomas. Strong nuclear and cytoplasmic expression of Nrf2 could be detected in these tumours. Prx I expression was significantly associated with cytoplasmic and nuclear Nrf2 expression. Prx I expression was also associated with tumour site, with cerebellar ependymomas having a lower expression of Prx I than other tumours. DJ-1 did not associate with Prxs but nuclear DJ-1 had an inverse association with nuclear Nrf2. Cytoplasmic DJ-1 associated with worse survival in ependymoma patients.

Conclusions: This study indicates that oxidative mechanisms as reflected by Nrf2 expression are highly activated in ependymomas. Prxs, especially Prx I, were associated with Nrf2 expression, suggesting a role for Nrf2 in Prx I synthesis in ependymomas. While DJ-1 did not associate with any of the Prxs, its expression was associated with worsened patient survival and could have a role as a prognostic marker in ependymomas.