نبذة مختصرة : JAK2V617F is the most common oncogenic lesion in patients with myeloproliferative neoplasms (MPNs). Despite the ability of JAK2V617F to instigate DNA damage in vitro, MPNs are nevertheless characterized by genomic stability. In this study, we address this paradox by identifying the DNA helicase RECQL5 as a suppressor of genomic instability in MPNs. We report increased RECQL5 expression in JAK2V617F-expressing cells and demonstrate that RECQL5 is required to counteract JAK2V617F-induced replication stress. Moreover, RECQL5 depletion sensitizes JAK2V617F mutant cells to hydroxyurea (HU), a pharmacological inducer of replication stress and the most common treatment for MPNs. Using single-fiber chromosome combing, we show that RECQL5 depletion in JAK2V617F mutant cells impairs replication dynamics following HU treatment, resulting in increased double-stranded breaks and apoptosis. Cumulatively, these findings identify RECQL5 as a critical regulator of genome stability in MPNs and demonstrate that replication stress-associated cytotoxicity can be amplified specifically in JAK2V617F mutant cells through RECQL5-targeted synthetic lethality. ; This work was supported by the NIH (K08 HL109734 to AM) and the MPN Research Foundation (AM). A.M. receives support from the Jeanne D. Housman Fund for Research on Myeloproliferative Disorders and is a recipient of a Damon Runyon clinical investigator award. EC is a recipient of a Lady Tata Memorial Trust Award. ; This is the final version of the article. It was first available from Elsevier via http://dx.doi.org/10.1016/j.celrep.2015.11.037
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