Differential expression of CAF-1 subunits in neuroblastoma cell lines after treatment with epigenetic modifying compounds

Neuroblastoma (NB), the most frequent extracranial solid malignancy in pediatric patients, arises from the embryonic neural crest cells that undergo transformation because of a blockage in differentiation. The long-term survival rate of patients with NB is less than 50%, and metastases are frequent in high-risk patients. Metastatic disease presents one of the biggest obstacles to successful treatment. Recently, two important cell phenotypes have been described in NB, referred to as mesenchymal (MES) and adrenergic (ADR). Frequent interconversion between those phenotypes, explicitly from ADR to MES presents one additional challenge to treatments, as MES profile is shown to be more resistant to current treatments, including chemotherapy. As shown by us and the others, MES and ADR phenotype do not differ in their genome, but in their epigenome, thus presenting differential gene expression pattern. Chromatin assembly factor 1 (CAF-1), and its subunits, specifically CHAF1A and CHAF1B, have been characterized as proteins of diagnostic value in many other solid tumors. In NB, CHAF1A shows increased levels in high-risk patients, while CHAF1B plays an important role in prognosis of metastatic tendencies of NB. In this thesis work, I investigated how the histone chaperones and epigenetic regulators CHAF1A and CHAF1B contribute to the maintenance of two principal NB cell phenotypes, and how their levels differ after the treatment with epigenetic modifying compounds. To this end, Western blot and quantitative real-time PCR were used to examine their protein and mRNA level, respectively, in a cohort of NB cell lines.