Oncogene and tumour suppressor: The two faces of SnoN

Abstract

SnoN was first identified based on its homology with the proto-oncogene c-Ski, and has since been implicated as a promoter of oncogenic transformation and cancer progression. Consistent with a role as proto-oncogene, SnoN negatively regulates TGF-b signalling, through its interactions with Smad complexes. Thus, SnoN inhibits the growth inhibitory effect of TGF-b, which is considered as the basis for the tumour suppressor activity of TGF-b signalling. In this issue of The EMBO Journal, Pan et al (2009) now demonstrate that SnoN also functions as a tumour suppressor, independently of its role in Smad signalling. The tumour suppressor role of SnoN results from its interaction with the promyelocytic leukaemia (PML) protein and the accumulation of SnoN in PML nuclear bodies, thus allowing SnoN to stabilize p53 and induce premature senescence. © 2009 European Molecular Biology Organization | All Rights Reserved.