18P - AURKB inhibition radiosensitises NSCLC by altering mitotic fate

Background

Lung cancer accounts for 18% of cancer-related deaths globally, due to its high incidence and mortality rates. Radiotherapy is standard of care but radioresistance remains an area of clinical need. Aurora kinase B (AURKB) is a mitotic kinase with links to DNA damage repair (DDR). Given AURKB’s canonical functions in mitotic progression and its interactions with DDR proteins such as p53, Ku70 and H2AX, we hypothesized that inhibition of AURKB via the clinical inhibitor Barasertib (AZD1152) would radiosensitise NSCLC.

Methods

H460 cells were used as a NSCLC in vitro model. Survival fraction was assessed by clonogenic assay. Mitotic phenotypes and DDR markers were analysed by immunofluorescence. Phospho-Mass spectrometry (MS) was carried out on a Thermo Orbitrap LC-MS with TMT tagging and phospho-peptide enrichment using TiO2 beads. In vivo experiments were performed using a H460 xenograft model in Balb/c nude mice.

Results

We found that AURKB inhibition by Barasertib and siRNA radiosensitises NSCLC in vitro. We assessed changes in peptide phosphorylation using global phospho-MS. Comparing IR and IR-Barasertib conditions, significant changes in phospho-peptides representing proteins involved in cell cycle regulation, DDR and survival signalling were observed. Consistent with this we found significant changes in the mitotic response of cells to IR when co-treated with Barasertib. There were greater mitotic defects in Barasertib treated cells including centrosomal amplification and chromosomal segregation defects. Live cell microscopy indicated that Barasertib treatment leads to greater mitotic duration, increased occurrences of slippage, abscission regression and mitotic death compared with IR alone. Interestingly in contrast to indications of the phospho-MS data no change in the DNA repair dynamics of interphase cells was found. Trials are underway to test the efficacy of the IR-Barasertib combination on tumour growth in vivo.

Conclusions

In conclusion, Barasertib radiosensitises NSCLC cells by disrupting mitotic fate. This holds promise for clinical application in highly proliferative tumours.

Editorial acknowledgement

Clinical trial identification

Legal entity responsible for the study

The authors.

Funding

MRC DiMen DTP Weston Park Cancer Charity.

Disclosure

C.E. Eyers: Non-Financial Interests, Institutional, Advisory Board, Panel member: BBSRC. All other authors have declared no conflicts of interest.