PT  - JOURNAL ARTICLE
AU  - Julieta Martino
AU  - Sebastián O. Siri
AU  - Natalia S. Paviolo
AU  - Cintia Garro
AU  - María F. Pansa
AU  - Sofía Carbajosa
AU  - Aaron C. Brown
AU  - José L. Bocco
AU  - Israel Gloger
AU  - Gerard Drewes
AU  - Kevin P. Madauss
AU  - Gastón Soria
AU  - Vanesa Gottifredi
TI  - Inhibitors of ROCK kinases induce multiple mitotic defects and synthetic lethality in BRCA2-deficient cells
AID  - 10.1101/2022.06.24.497514
DP  - 2022 Jan 01
TA  - bioRxiv
PG  - 2022.06.24.497514
4099  - http://biorxiv.org/content/early/2022/06/28/2022.06.24.497514.short
4100  - http://biorxiv.org/content/early/2022/06/28/2022.06.24.497514.full
AB  - BRCA2-deficient cells are highly sensitive to poly-ADP-ribose polymerase inhibitors (PARPi) due to their impaired homologous recombination repair. This increased cytotoxicity is triggered by DNA replication stress induced by PARP trapping on DNA. Thus, it is broadly assumed that DNA damage is a prerequisite for BRCA2 synthetic lethality (SL). Here we show that inhibiting ROCK kinases in BRCA2 deficient cells, triggers SL independently from acute replication stress. In contrast, such SL is preceded by enhanced M-phase defects such as anaphase bridges, and abnormal mitotic figures, which were associated with multipolar spindles, supernumerary centrosomes and multinucleation. SL was also triggered by inhibiting Citron Rho-interacting kinase, another enzyme which, similarly to ROCK kinases, regulates cytokinesis. Together, these observations suggest cytokinesis failure as trigger of mitotic abnormalities and SL in BRCA2 cells. Furthermore, preventing mitotic entry by Early mitotic inhibitor 1 (EMI1) depletion promoted survival of BRCA2 deficient cells treated with inhibitors of ROCK kinases, thus reinforcing the association between M-phase and the cell death in BRCA2 deficient cells. This novel mechanism of SL induction is in contrast to the one triggered by PARPi and uncovers mitosis as an Achilles heel of BRCA2 deficient cells.Competing Interest StatementThe authors have declared no competing interest.