Abstract
Background: Kinases are emerging as promising targetable choices for Triple negative breast cancer (TNBC) patients who suffer from lack of targeted therapy. Aurora kinase A (AURKA) inhibitor alisertib although showed promise but failed to impart any ultimate benefit in TNBCs. Considering initial preclinical success of alisertib, this study tried to explore the underlying mechanisms of its subsequent insensitivity in TNBCs. Methods: Breast cancer kinome was screened for kinases with high clinical significance by clinical kinase indexing coupled with studying their differential expression pattern and prognostic impact using available datasets. Relevant kinase inhibitors were assessed for pharmacological/toxicological parameters in silico. Alisertib induced polyploid giant cancer cells (PGCCs) were observed microscopically and flow cytometrically. PGCC viability was assessed by single cell MTT and (BrdU) assay. Epithelial and mesenchymal transition (EMT) and stemness markers were examined by immunofluorescence. PGCC enrichment was additionally checked in stained tissue explant/histocultures. Alisertib insensitive cells were developed by repeated alisertib pulsing as confirmed by MTT assay. Alisertib insensitive mammospheres were targeted with mifepristone. Results: Clinical Kinase Index (CKI) scoring and pan cancer expressional profiling coupled with analysis of prognostic effect revealed AURKA as a targetable prognostically relevant kinase. AURKA-targeting agent alisertib demonstrated acceptable pharmacological/toxicological properties but enriched PGCCs in in vitro and tumour histocultures. PGCCs maintained replicative potency producing viable progenies. They retained expression of EMT and stemness markers; demonstrating single cell clonogenicity. PGCC enrichment led to reduced alisertib sensitivity as evident from enrichment of insensitive mammospheres, targetable by mifepristone. Conclusion: PGCCs contributed to alisertib insensitivity in TNBCs that may be targeted by mifepristone.