CDK2 Inhibition Produces a Persistent Population of Polyploid Cancer Cells

Aneuploidy, a cancer hallmark, drives chromosomal instability, drug resistance, and clinically-aggressive tumors. Cyclin-dependent kinase 2 (CDK2) antagonism with independent inhibitors or CDK2 knock-down triggered anaphase catastrophe. This disrupts supernumerary centrosome clustering, causing multipolar division and apoptosis. Time-lapse fluorescent microscopy of FUCCI cell cycle probes transduced into aneuploid lung cancer cells revealed distinct fates of bipolar and polyploid cells after CDK2 inhibition. Apoptosis occurred in multipolar progeny but was repressed in persistent polyploid cancer cells. RNA-seq analyses after CDK2 inhibition of 4N versus 2N lung cancer cells were enriched for CDK1 pathway and KIF family members. The Cancer Genome Atlas (TCGA) analysis of lung cancers indicated CDK1 and KIF family member overexpression was associated with an unfavorable survival. Intravital microscopy of transplanted lung cancer cells in mice extended findings from the in vitro to in vivo settings. CDK2 inhibition of tumor-bearing mice produced polyploid cancer cells in vivo. These cancer cells were resistant to apoptosis and proliferated despite CDK2 inhibition. In contrast, polyploid populations were rarely detected in CDK2 inhibited human alveolar epithelial cells. These findings are translationally relevant. Combined targeting of CDK2 with CDK1 or kinesin family member antagonists should eliminate polyploid cancer cells, promote apoptosis and augment antineoplastic effects. ED1SQ4 lung cancer cells treated with vehicle as a control or CYC065 (0.5M) for 72 hours were stained with Vybrant™ DyeCycle™ Green Stain (#V35005, ThermoFisher) for 1 hour. Cells were then washed with phosphate buffered saline (PBS) and then sorted for diploid and for polyploid populations by S3e Cell Sorter (Bio-RAD) based on DNA quantification.