Abstract 1555: CDK2 inhibition & disruption of centrosome stoichiometry: a clinically tractable death program for aneuploid cancer cells
Authors: Chen Zibo , Liu Xi , Kawakami Masanori , Liu Xiuxia , Baker Allison , Bhatawadekar Aayush , Tyutyunyk-Massey Liliya , Dmitrovsky Ethan , Narayan Kedar 
Published: June 2023

Abstract
Genomic instability is a cancer hallmark. Aberrant centrosome numbers often occur in cancer and is associated with genomic instability. Mitosis with supernumerary centrosomes leads to abnormal chromosome segregation and aneuploidy in progeny cells. While many cells with abnormal chromosomes are eliminated through apoptosis, some gain a growth advantage and acquire resistance to antineoplastic agents. This aneuploidy is associated with aggressive tumor biology and unfavorable clinical outcomes. Cyclin-dependent kinase 2 (CDK2) plays a major role regulation of cell cycle progression, centrosome duplication and clustering. We previously reported that CDK2 inhibition prevented supernumerary centrosomes clustering, causing multipolar mitosis and anaphase catastrophe in lung and other aneuploid cancers. To elucidate engaged mechanisms focused ion beam scanning electron microscope (FIB-SEM) and immunofluorescent staining were each used to interrogate the ultrastructure of multipolar mitosis after CDK2 inhibition by CYC065-treatment (a CDK2/9 inhibitor). CYC065-treatment induced distinct ultrastructural changes in aneuploid lung cancer cells including formation of chromosome rings and multipolarity. As compared to vehicle controls, CYC065-treatment markedly extended the duration of chromosome rings in lung cancer cells and conferred aberrant mitosis in live cell imagining. Intriguingly, this treatment disrupted centrosome and centriole stoichiometry in cells with chromosome rings or multipolarity. These findings were confirmed using immunofluorescence assays of lung and other cancer cells having supernumerary centrosomes. To elucidate if CDK2 or CDK9 activity directly altered centriole stoichiometry, chromosome rings or multipolarity, immunofluorescent assays were performed in lung cancer cells that independently knocked down CDK2 or CDK9 using siRNAs relative to controls. Centriole stoichiometry abnormalities in cancer cells having chromosome rings or multipolarity were statistically significantly higher in CDK2 knock-down but not in CDK9 knock-down transfectants or controls. Engineered gain of CDK2 but not CDK9 expression rescued CYC065 mediated chromosome rings and multipolarity in aneuploid lung cancer cells. Taken together, this study uncovered that CDK2 inhibition disrupted centrosome stoichiometry, causing apoptotic death of aneuploid cancer cells. This is a clinically-tractable pharmacologic mechanism that conferring cancer cell death. Current work determines if similar mechanisms are engaged in vivo in syngeneic mouse lung cancer models undergoing CDK2 antagonism.
Citation Format: Zibo Chen, Xi Liu, Masanori Kawakami, Xiuxia Liu, Allison Baker, Aayush Bhatawadekar, Liliya Tyutyunyk-Massey, Ethan Dmitrovsky, Kedar Narayan. CDK2 inhibition & disruption of centrosome stoichiometry: a clinically tractable death program for aneuploid cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1555.