The WRN and MUS81 proteins limit cell death and genome instability following oncogene activation

• Published in: Oncogene Vol. 32; no. 5; pp. 610 - 620
• Main Authors: Murfuni, I, Nicolai, S, Baldari, S, Crescenzi, M, Bignami, M, Franchitto, A, Pichierri, P
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 31.01.2013; Nature Publishing Group
• Subjects: 631/208/737/211; 631/67/395; 631/80/641/151/2357; 631/80/82; Apoptosis; Cancer; Cancer cells; Cell Biology; Cell Cycle; Cell Death; Chromosome Fragile Sites; Cyclin E - genetics; Cytogenetics; DNA Breaks, Double-Stranded; DNA damage; DNA helicase; DNA Replication; DNA-Binding Proteins - metabolism; E2F1 Transcription Factor - genetics; Endonuclease; Endonucleases - metabolism; Exodeoxyribonucleases - metabolism; Fragile sites; Genetic aspects; Genomes; Genomic Instability; Genomics; Health aspects; Helicases; Human Genetics; Humans; Internal Medicine; Medicine; Medicine & Public Health; Molecular modelling; Mus81 protein; Oncogenes; Oncology; original-article; Overexpression; Physiological aspects; Proteins; RecQ Helicases - metabolism; RecQ protein; Replication; Replication forks; Stress; Tumors; Up-Regulation; Werner Syndrome Helicase; WRN protein; Italy; replication fork arrest; Werner syndrome; genome instability; RecQ helicases
• ISSN: 0950-9232; 1476-5594
• DOI: 10.1038/onc.2012.80

Oncogene-induced replication stress is recognized as the primary cause of accumulation of DNA damage and genome instability in precancerous cells. Although the molecular mechanisms responding to such type of replication perturbation are not fully characterized, it has been speculated that their dysfunction may enhance genome instability and accelerate tumor progression. Here, we show that the WRN protein, a member of the human RecQ helicases, is necessary to sustain replication fork progression in response to oncogene-induced replication stress. Loss of WRN affects cell cycle progression and results in enhanced accumulation of double-strand breaks and instability at common fragile sites in cells experiencing oncogene-induced replication stress. Moreover, we demonstrate that double-strand breaks, observed upon oncogene over-expression, depend on the MUS81 endonuclease, which represents a parallel pathway collaborating with WRN to prevent cell death. Overall, our findings give insights into the mechanisms protecting replication forks in cells experiencing oncogene-induced replication stress, and identify factors that, when mutated or dysfunctional, may enhance genome instability in precancerous cells. In addition, because concomitant depletion of WRN and MUS81 causes synthetic sickness in cells growing under oncogene-induced replication stress, our results support the possibility of targeting cancer cells with an impaired replication fork recovery pathway by a specific inactivation of the other parallel pathway.