title: High-content, high-throughput analysis of cell cycle perturbations induced by the HSP90 inhibitor XL888.
abstract: 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.
  
  
  RESULTS
  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
  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.
authors.affiliation: Department of Molecular and Cellular Pharmacology, Exelixis, Inc., South San Francisco, California, United States of America. xl888.mail@gmail.com
authors.forename: Susan K
authors.initials: SK
authors.lastname: Lyman
authors.forename: Suzanne C
authors.initials: SC
authors.lastname: Crawley
authors.forename: Ruoyu
authors.initials: R
authors.lastname: Gong
authors.forename: Joanne I
authors.initials: JI
authors.lastname: Adamkewicz
authors.forename: Garth
authors.initials: G
authors.lastname: McGrath
authors.forename: Jason Y
authors.initials: JY
authors.lastname: Chew
authors.forename: Jennifer
authors.initials: J
authors.lastname: Choi
authors.forename: Charles R
authors.initials: CR
authors.lastname: Holst
authors.forename: Leanne H
authors.initials: LH
authors.lastname: Goon
authors.forename: Scott A
authors.initials: SA
authors.lastname: Detmer
authors.forename: Jana
authors.initials: J
authors.lastname: Vaclavikova
authors.forename: Mary E
authors.initials: ME
authors.lastname: Gerritsen
authors.forename: Robert A
authors.initials: RA
authors.lastname: Blake
mesh_terms: D053961:Azabicyclo Compounds / Q000494:pharmacology*; D016227:Benzoquinones / Q000494:pharmacology; D002453:Cell Cycle / Q000187:drug effects; D018797:Cell Cycle Proteins / Q000378:metabolism; D002460:Cell Line; D005434:Flow Cytometry; D018841:HSP90 Heat-Shock Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D057166:High-Throughput Screening Assays / Q000379:methods*; D006801:Humans; D047029:Lactams, Macrocyclic / Q000494:pharmacology; D010795:Phthalic Acids / Q000494:pharmacology*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D013997:Time Factors; D000097869:Polo-Like Kinase 1
chemical_list: D053961:Azabicyclo Compounds; D016227:Benzoquinones; D018797:Cell Cycle Proteins; D018841:HSP90 Heat-Shock Proteins; D047029:Lactams, Macrocyclic; D010795:Phthalic Acids; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins; D000097869:Polo-Like Kinase 1; C559121:XL 888; C112765:tanespimycin