The nucleolus as a fundamental regulator of the p53 response and a new target for cancer therapy.

BACKGROUND: Recent studies have highlighted the fundamental role that key oncogenes such as MYC, RAS and PI3K occupy in driving RNA Polymerase I transcription in the nucleolus. In addition to maintaining essential levels of protein synthesis, hyperactivated ribosome biogenesis and nucleolar function plays a central role in suppressing p53 activation in response to oncogenic stress. Consequently, disruption of ribosome biogenesis by agents such as the small molecule inhibitor of RNA Polymerase I transcription, CX-5461, has shown unexpected, potent, and selective effects in killing tumour cells via disruption of nucleolar function leading to activation of p53, independent of DNA damage. SCOPE OF REVIEW: This review will explore the mechanism of DNA damage-independent activation of p53 via the nucleolar surveillance pathway and how this can be utilised to design novel cancer therapies. MAJOR CONCLUSION AND GENERAL SIGNIFICANCE: Non-genotoxic targeting of nucleolar function may provide a new paradigm for treatment of a broad range of oncogene-driven malignancies with improved therapeutic windows. This article is part of a Special Issue entitled: Translation and Cancer.