title: HSP90 inhibitor CH5164840 induces micronuclei in TK6 cells via an aneugenic mechanism.
abstract: Heat-shock protein 90 (HSP90) is a promising druggable target for therapy of conditions including cancer, renal disease, and chronic neurodegenerative diseases. Despite the possible beneficial effects of HSP90 inhibitors, some of these agents present a genotoxicity liability. We have examined the mode of action of micronucleus formation in TK6 cells by a novel and highly specific HSP90 inhibitor, CH5164840, by means of an in vitro micronucleus test with fluorescence in situ hybridization (FISH), γH2AX staining to detect DNA damage, and microscopic observation of chromosomal alignment in mitotic cells. The percentage of centromere-positive micronuclei induced by CH5164840 (FISH analysis) was significant, but the percentage of centromere-negative ones was not, suggesting that induction of micronuclei was due to a mechanism of aneugenicity rather than DNA reactivity. This conclusion was further supported by the result of co-staining γH2AX and the apoptosis marker caspase-3; the predominant elevation of apoptotic γH2AX rather than non-apoptotic γH2AX indicated little involvement of DNA-reactivity mechanisms. Microscopic observation revealed asymmetric spindle microtubules and chromosomal misalignment of metaphase cells. These data indicated that CH5164840 causes spindle dysfunction that induces micronuclei. The risk/benefit ratio must be considered in the development of HSP90 inhibitors.
authors.affiliation: Research Division, Chugai Pharmaceutical Co., Ltd., Gotemba, Shizuoka 412-8513, Japan.
authors.forename: Kaori
authors.initials: K
authors.lastname: Matsuzaki
authors.affiliation: Research Division, Chugai Pharmaceutical Co., Ltd., Gotemba, Shizuoka 412-8513, Japan.
authors.forename: Asako
authors.initials: A
authors.lastname: Harada
authors.affiliation: Research Division, Chugai Pharmaceutical Co., Ltd., Gotemba, Shizuoka 412-8513, Japan.
authors.forename: Kenji
authors.initials: K
authors.lastname: Tanaka
authors.affiliation: Research Division, Chugai Pharmaceutical Co., Ltd., Gotemba, Shizuoka 412-8513, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Takeiri
authors.affiliation: Research Division, Chugai Pharmaceutical Co., Ltd., Gotemba, Shizuoka 412-8513, Japan. Electronic address: mishimamsy@chugai-pharm.co.jp.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Mishima
mesh_terms: D024422:Aneugens / Q000494:pharmacology*; D016227:Benzoquinones / Q000494:pharmacology*; D002478:Cells, Cultured; D004249:DNA Damage; D004305:Dose-Response Relationship, Drug; D018841:HSP90 Heat-Shock Proteins / Q000037:antagonists & inhibitors; D006801:Humans; D047029:Lactams, Macrocyclic / Q000494:pharmacology*; D008214:Lymphocytes / Q000187:drug effects* / Q000378:metabolism; D048629:Micronuclei, Chromosome-Defective / Q000139:chemically induced*; D015162:Micronucleus Tests; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics
chemical_list: D024422:Aneugens; D016227:Benzoquinones; C570831:CH5164840; D018841:HSP90 Heat-Shock Proteins; D047029:Lactams, Macrocyclic
keywords: Aneugen; FISH; HSP90; γH2AX