Neuroblastoma is the most frequent extra cranial solid tumour in children and accounts for about 15% of pediatric oncology death. We have identified a new protein, poly(ADP-ribose)polymerase-3 (PARP-3), that could contribute to the development of this cancer. PARP-3 is associated with a group of proteins called Polycomb (PcG). PcG represses the expression of several genes by altering the structure of chromatin (packaged DNA) to maintain cellular identity during development. However, overexpression of PcG proteins, which is a hallmark of several cancers, causes alterations in the expression of tumour suppressors, causing unplanned cellular proliferation. The purpose of this project is to gain a better understanding of the regulatory function of PARP-3 in PcG complexes in the development of neuroblastoma. Several PARP inhibitors have been developed for the treatment of many cancers. Studying the role of PARP-3 could define a new therapeutic avenue for neuroblastoma.