Aneuploidy generates proteotoxic stress and DNA damage concurrently with p53-mediated post-mitotic apoptosis in SAC-impaired cells

Akihiro Ohashi,Hitoshi Kandori,Tomohiro Kawamoto,Takaharu Hirayama,Maki Miyamoto,Tomoyasu Ishikawa,Kentaro Iwata,Hiroshi Banno,Tadahiro Nambu,Momoko Ohori,Masanori Okaniwa,Kenichi Iwai,Daisuke Morishita,Yusuke Nakayama

doi:10.1038/ncomms8668

Abstract

The molecular mechanism responsible that determines cell fate after mitotic slippage is unclear. Here we investigate the post-mitotic effects of different mitotic aberrations—misaligned chromosomes produced by CENP-E inhibition and monopolar spindles resulting from Eg5 inhibition. Eg5 inhibition in cells with an impaired spindle assembly checkpoint (SAC) induces polyploidy through cytokinesis failure without a strong anti-proliferative effect. In contrast, CENP-E inhibition causes p53-mediated post-mitotic apoptosis triggered by chromosome missegregation. Pharmacological studies reveal that aneuploidy caused by the CENP-E inhibitor, Compound-A, in SAC-attenuated cells causes substantial proteotoxic stress and DNA damage. Polyploidy caused by the Eg5 inhibitor does not produce this effect. Furthermore, p53-mediated post-mitotic apoptosis is accompanied by aneuploidy-associated DNA damage response and unfolded protein response activation. Because Compound-A causes p53 accumulation and antitumour activity in an SAC-impaired xenograft model, CENP-E inhibitors could be potential anticancer drugs effective against SAC-impaired tumours.

Highlights

The molecular mechanism responsible that determines cell fate after mitotic slippage is unclear
We reveal that under spindle assembly checkpoint (SAC)-defective conditions, aneuploidy caused by CENP-E inhibition triggers p53 activation after mitotic slippage, resulting in a post-mitotic decrease in proliferation
To evaluate the potential of CENP-E as a cancer therapeutic target, we investigated the molecular mechanisms by which CENP-E regulates cancer cell proliferation using short interfering RNA (siRNA)-based approaches

Summary

Introduction

The molecular mechanism responsible that determines cell fate after mitotic slippage is unclear. BubR1 knockdown (siBubR1) released both siCENP-Eand siEg5-transfected cells from prolonged mitotic arrest (Supplementary Fig. 1d), demonstrating that BubR1 monitored aberrant chromosome dynamics caused by siCENP-E or siEg5 and triggered SAC activation. In siCENP-E þ siBubR1 transfection experiments, the cells exited prolonged mitotic arrest (Supplementary Fig. 1d), and cell viability was rescued on day 2 (Fig. 1b).

Results

Conclusion