Overexpression of Long Noncoding RNA HOTAIR Is a Unique Epigenetic Characteristic of Myxopapillary Ependymoma.

Ependymomas are a heterogeneous group of central nervous system tumors. Despite the recent advances, there are no specific biomarkers for ependymomas. In this study, we explored the role of homeobox (HOX) genes and long noncoding RNA (LncRNA) HOTAIR in ependymomas along the neural axis. Bioinformatics analysis was performed on publicly available gene expression data. Quantitative RT-PCR was used to determine the mRNA expression level among different groups of ependymomas. RNA in situ hybridization (ISH) with probes specific to HOTAIR was performed on tumor tissue microarray (TMA) constructed with 19 ependymomas formalin-fixed paraffin-embedded tissue. Gene expression analysis revealed higher expression of posterior HOX genes and HOTAIR in myxopapillary ependymoma (MPE), in comparison to other spinal and intracranial ependymoma. qRT-PCR confirmed the high HOXD10 expression in spinal MPEs. There was a significant upregulation of HOTAIR expression in spinal MPE and elevated HOTAIR expressions were further confirmed by RNA ISH on the TMA. Intriguingly, HOXD10 and HOTAIR expressions were not elevated in nonependymoma spinal tumors. Our collective results suggest an important role for the lncRNA HOTAIR and posterior HOX genes in the tumorigenesis of spinal MPE. HOTAIR may also serve as a potential diagnostic marker for spinal MPE.