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Updated: Jun 3, 2026
Analysis of Cell Cycle Position in Mammalian Cells
Published on: January 21, 2012
High-content, high-throughput analysis of cell cycle perturbations induced by the HSP90 inhibitor XL888
Susan K Lyman1, Suzanne C Crawley, Ruoyu Gong
1Department of Molecular and Cellular Pharmacology, Exelixis, Inc., South San Francisco, California, United States of America. xl888.mail@gmail.com
Background:
Many proteins that are dysregulated or mutated in cancer cells rely on the molecular chaperone HSP90 for their proper folding and activity, which has led to considerable interest in HSP90 as a cancer drug target. The diverse array of HSP90 client proteins encompasses oncogenic drivers, cell cycle components, and a variety of regulatory factors, so inhibition of HSP90 perturbs multiple cellular processes, including mitogenic signaling and cell cycle control. Although many reports have investigated HSP90 inhibition in the context of the cell cycle, no large-scale studies have examined potential correlations between cell genotype and the cell cycle phenotypes of HSP90 inhibition.
Methodology/Principal Findings:
To address this question, we developed a novel high-content, high-throughput cell cycle assay and profiled the effects of two distinct small molecule HSP90 inhibitors (XL888 and 17-AAG [17-allylamino-17-demethoxygeldanamycin]) in a large, genetically diverse panel of cancer cell lines. The cell cycle phenotypes of both inhibitors were strikingly similar and fell into three classes: accumulation in M-phase, G2-phase, or G1-phase. Accumulation in M-phase was the most prominent phenotype and notably, was also correlated with TP53 mutant status. We additionally observed unexpected complexity in the response of the cell cycle-associated client PLK1 to HSP90 inhibition, and we suggest that inhibitor-induced PLK1 depletion may contribute to the striking metaphase arrest phenotype seen in many of the M-arrested cell lines.
Conclusions/Significance:
Our analysis of the cell cycle phenotypes induced by HSP90 inhibition in 25 cancer cell lines revealed that the phenotypic response was highly dependent on cellular genotype as well as on the concentration of HSP90 inhibitor and the time of treatment. M-phase arrest correlated with the presence of TP53 mutations, while G2 or G1 arrest was more commonly seen in cells bearing wt TP53. We draw upon previous literature to suggest an integrated model that accounts for these varying observations.
Insights
HSP90 inhibitors cause cell cycle arrest, with M-phase arrest linked to TP53 mutations. This study reveals genotype-dependent cell cycle phenotypes from HSP90 inhibition in diverse cancer cell lines.
Area of Science:
- Oncology
- Molecular Biology
- Genetics
Background:
- Heat shock protein 90 (HSP90) is crucial for stabilizing many cancer-driving proteins.
- Inhibiting HSP90 disrupts cancer cell processes like cell cycle control and signaling.
- Previous studies lacked large-scale analysis of genotype-phenotype correlations in HSP90 inhibition.
Purpose of the Study:
- To investigate the relationship between cancer cell genotype and cell cycle response to HSP90 inhibition.
- To characterize cell cycle phenotypes induced by HSP90 inhibitors across a diverse panel of cancer cell lines.
Main Methods:
- Developed a novel high-content, high-throughput cell cycle assay.
- Screened two HSP90 inhibitors (XL888 and 17-AAG) in a large, genetically diverse cancer cell line panel.
- Analyzed cell cycle distribution (G1, G2, M-phase) and correlated phenotypes with TP53 mutational status.
Main Results:
- HSP90 inhibition induced three main cell cycle phenotypes: M-phase, G2-phase, or G1-phase accumulation.
- M-phase arrest was the most common phenotype and significantly correlated with TP53 mutant status.
- TP53 wild-type cells predominantly showed G1 or G2 arrest.
- Observed complex regulation of PLK1, a cell cycle client, suggesting its role in metaphase arrest.
Conclusions:
- Cell cycle response to HSP90 inhibitors is strongly dependent on cancer cell genotype, drug concentration, and treatment time.
- TP53 mutation status is a key determinant of cell cycle arrest phenotype following HSP90 inhibition.
- An integrated model is proposed to explain the varying cell cycle responses based on genotype and drug treatment parameters.
