Expression of the HOX genes and HOTAIR in atypical teratoid rhabdoid tumors and other pediatric brain tumors.

Pediatric brain tumors such as atypical teratoid rhabdoid tumors (ATRTs) are highly aggressive and predominantly occur in young children. A characteristic feature of ATRT is aberrations of the SMARCB1 (hSNF5/INI1) gene. Developmental gene defects may play an important role in the biology of pediatric brain tumors. HOX genes are transcription factors that play a pivotal role in anterior-posterior body axis patterning and are misexpressed in tumors such as lung carcinoma, neuroblastoma, and glioma. HOX genes are also known to be associated with long noncoding RNAs (lncRNAs) such as HOTAIR, which induces transcriptional silencing of the HOXD locus by recruiting polycomb repressive complex 2 to the HOXD locus. In this study, transcriptome analysis using the nanoString platform was performed, and expression of the HOX and HOTAIR genes was studied in pediatric tumors: 20 ATRTs, 10 ependymomas, 10 medulloblastomas, six glioblastoma multiforme, and nine juvenile pilocytic astrocytomas (JPAs). Results indicate that in ATRTs, medulloblastomas, and JPAs, the HOTAIR and HOXC genes are highly expressed; however, HOXD8-10 genes are not silenced. In ependymomas, there is low expression of the HOXC, HOTAIR, and HOXD8-10 genes. These interesting results need to be elucidated further so that the functions of these genes in pediatric tumors is understood.