Imbalance of the spindle-assembly checkpoint promotes spindle poison-mediated cytotoxicity with distinct kinetics

Abstract

Disrupting microtubule dynamics with spindle poisons activates the spindle-assembly checkpoint (SAC) and induces mitotic cell death. However, mitotic exit can occur prematurely without proper chromosomal segregation or cytokinesis by a process termed mitotic slippage. It remains controversial whether mitotic slippage increases the cytotoxicity of spindle poisons or the converse. Altering the SAC induces either mitotic cell death or mitotic slippage. While knockout of MAD2-binding protein p31 comet strengthened the SAC and promoted mitotic cell death, knockout of TRIP13 had the opposite effect of triggering mitotic slippage. We demonstrated that mitotic slippage prevented mitotic cell death caused by spindle poisons, but reduced subsequent long-term survival. Weakening of the SAC also reduced cell survival in response to spindle perturbation insufficient for triggering mitotic slippage, of which mitotic exit was characterized by displaced chromosomes during metaphase. In either mitotic slippage or mitotic exit with missegregated chromosomes, cell death occurred only after one cell cycle following mitotic exit and increased progressively during subsequent cell cycles. Consistent with these results, transient inhibition of the SAC using an MPS1 inhibitor acted synergistically with spindle perturbation in inducing chromosome missegregation and cytotoxicity. The specific temporal patterns of cell death after mitotic exit with weakened SAC may reconcile the contradictory results from many previous studies.

Targeting LDHC dysregulates the cell cycle and improves sensitivity to cisplatin and olaparib

“…Moreover, their expression does not decline to baseline levels after the first round of mitosis (20-24 h). In concordance with our cell cycle profiling data, these observations suggest that LDHC silencing may result in two cell subpopulations, whereby one subset of cells undergoes mitotic slippage and the other experiences prolonged pre-mitotic arrest with likely subsequent cell death as a result of excessive, unrepaired DNA damage (Brito & Rieder, 2006; Zeng et al , 2019). Indeed, it is well known that the balance of two opposing networks, involving cyclin B1 degradation and caspase cleavage, determine mitotic cell fate (Topham & Taylor, 2013).…”

Co-Adjuvant Therapy Efficacy of Catechin and Procyanidin B2 with Docetaxel on Hormone-Related Cancers In Vitro

“…In addition, inactivating CDK1 agents can induce long-term cytotoxicity (clonogenic assay) [116]. In the present study, we observed that MCF-7 cells treated with CAT plus DOCE and ProB2 plus DOCE caused a high increase in CDK1 inhibitor.…”

Integrative oncogene-dependency mapping identifies RIT1 vulnerabilities and synergies in lung cancer

“…6c, d ). A weakened SAC via perturbation of key components has been associated with mitotic errors including misaligned chromosomes, chromosome bridges, micronuclei formation, and aneuploidy 63 – 66 . Consistent with RIT1 M90I suppression of the SAC, RIT1 -mutant cells showed significantly higher prevalence of chromosomal abnormalities compared to parental cells (Fig.…”