Overexpression of H2AFX gene in neuroblastoma is associated with worse prognosis.

ABSTRACT

BACKGROUND: Neuroblastoma (NB) is the most common solid tumour in childhood, and rises in the sympathetic nervous system. Here, we addressed the in silico analysis of the association between the expression of H2AFX gene involved in DNA damage response, and the survival of a cohort of 786 NB patients. METHODS: In silico gene expression was retrieved from the publicly available dataset summarised by Cangelosi et al., including 13,696 gene expression profiles of 786 NB tumours at onset of disease. The prognostic value of H2AFX (H2A histone family member X) gene expression for event-free survival (EFS) and overall survival (OS) was evaluated by Kaplan-Meier and Cox regression analysis. The main results were validated on another openly accessible in silico database (NRC-283) containing 13,489 gene expressions in 283 NB patients. The expression of H2AFX protein was then tested by immunofluorescence on 48 primary NB samples of different tumour stages. H2AFX activity as an oncogene has been further validated in vitro by silencing the molecule in two NB cell lines, characterised by MYCN amplified or not, and performing cell growth and migration assays. RESULTS: A strong inverse association between H2AFX expression and patients' survival was observed and confirmed by immunofluorescence results on primary NB tissue sections. Cox regression analysis also disclosed H2AFX as an independent predictor of EFS and OS. The gene-silencing experiments strongly suggested an oncogenic role for H2AFX on NB cells, regardless of MYCN amplification. CONCLUSIONS: H2AFX is a prognostic marker for unfavourable NB and could be considered a target for therapeutic interventions.