A guardian turned rogue: TP53 promoter translocations rewire stress responses to oncogenic effectors in osteosarcoma.

Osteosarcoma is the most prevalent malignant bone tumour in children, adolescents and young adults. Despite a multitude of aberrations present in osteosarcoma genomes, no recurrent driver mutations have been identified to date. In addition, unlike for other sarcoma entities, no functional fusion proteins resulting from chromosomal rearrangements have been reported. Part of the genetic complexity of osteosarcoma might, however, be explained by the association of osteosarcoma with germline and somatic mutations of the major tumour suppressor TP53 that safeguards genomic integrity. By demonstrating that TP53 promoter translocations resulting in transcriptionally active fusion genes are a recurrent event in osteosarcoma, long-learnt paradigms are challenged by a recent publication by Saba, Difilippo et al. Osteosarcoma no longer appears to be a fusion-negative tumour, and by hardwiring cellular stress responses that transactivate the TP53 promoter to an oncogenic fusion partner, TP53 can be subverted and turned into an oncogene.