Epigenetic Alterations in Meningiomas-A Review

While genetic alterations in meningiomas have long been the subject of research, the diagnostic and prognostic significance of epigenetic alterations in this most common type of human brain tumor has become increasingly evident in recent years. The most significant findings to date have been DNA methylation analyses and the resulting classification of meningiomas into statistical clusters with different prognoses and various prevailing molecular and phenotypic characteristics. Even the loss of trimethylation of lysine at position 27 in histone 3 (H3K27me3) is of major importance, as it is significantly associated with more aggressive tumor behavior and a poorer prognosis. Since there are far more than just these epigenetic aspects associated with meningiomas, and given the clinical significance of this tumor type, a comprehensive review is needed that reflects the current state of knowledge. We conducted a systematic literature search in PubMed using broad search terms covering all epigenetic modifications and all subcategories. The search was not limited to a specific time frame. The 513 references identified in this manner were fully analysed. To ensure a comprehensive review that covered all relevant topics and reflected the current state of knowledge, 196 references were included in the reference section. In addition to DNA methylation and forms of histone modification, the review includes known alterations in chromatin remodeling complexes, as well as alterations in various types of non-coding RNAs, such as microRNAs and circular RNAs. Moreover, the discussion also addresses epigenetic modifications relevant to oncology that have not yet been identified or investigated in meningiomas. Therefore, this review additionally provides an appropriate overview of epigenetic mechanisms and alterations in general. The broad spectrum of epigenetic alterations opens up far-reaching prospects for future forms of molecular therapy in patients with meningiomas; the current state of epigenetic molecular therapeutic approaches for meningiomas will be addressed in the final section of the discussion.