title: Small-molecule inhibitor BMS-777607 induces breast cancer cell polyploidy with increased resistance to cytotoxic chemotherapy agents.
abstract: The RON receptor tyrosine kinase is a therapeutic target for cancer treatment. Here, we report therapeutic effect and phenotypic change of breast cancer cells in response to BMS-777607, a RON tyrosine kinase inhibitor. Treatment of breast cancer cells with BMS-777607 at therapeutic doses inhibited cancerous clonogenic growth but had only minimal effect on cell apoptosis. Significantly, BMS-777607 induced extensive polyploidy with multiple sets of chromosomes in cancer cells. This effect is independent of RON expression. Knockdown of RON in T-47D and ZR-75-1 cells by specific siRNA did not prevent polyploid formation. Immunofluorescent analysis of α-tubulin and γ-tubulin expression in polyploid cells revealed that BMS-777607 disrupts bipolar spindle formation and causes multipolar-like microtubule assembly. Also, both metaphase equatorial alignment and chromosomal segregation were absent in polyploid cells. These results suggest that cellular mitosis arrests at prophase/pro-metaphase and fails to undergo cytokinesis. By analyzing kinase-inhibitory profiles, aurora kinase B was identified as the target molecule inhibited by BMS-777607. In BMS-777607-treated cells, aurora kinase B was inhibited followed by protein degradation. Moreover, BMS-777607 inhibited Ser10 phosphorylation of histone H3, a substrate of aurora kinase B. Chemosensitivity analysis indicated the resistance of polyploid cells toward chemotherapeutics. Treatment with doxorubicin, bleomycin, methotrexate, and paclitaxel significantly increased cellular IC50 values. These findings highlight the theory that BMS-777607 acts as a multikinase inhibitor at therapeutic doses and is capable of inducing polyploidy by inhibiting aurora kinase B. Increased resistance of polyploid cells to cytotoxic chemotherapeutics could have a negative impact on targeted cancer therapy using BMS-777607.
authors.affiliation: Cancer Biology Research Center, School of Pharmacy, Texas Tech University Health Sciences Center, Amarillo, TX 79106, USA.
authors.forename: Sharad
authors.initials: S
authors.lastname: Sharma
authors.forename: Jun-Ying
authors.initials: JY
authors.lastname: Zeng
authors.forename: Chun-Mei
authors.initials: CM
authors.lastname: Zhuang
authors.forename: Yong-Qing
authors.initials: YQ
authors.lastname: Zhou
authors.forename: Hang-Ping
authors.initials: HP
authors.lastname: Yao
authors.forename: Xing
authors.initials: X
authors.lastname: Hu
authors.forename: Ruiwen
authors.initials: R
authors.lastname: Zhang
authors.forename: Ming-Hai
authors.initials: MH
authors.lastname: Wang
mesh_terms: D000631:Aminopyridines / Q000494:pharmacology* / Q000633:toxicity; D064107:Aurora Kinase B / Q000037:antagonists & inhibitors; D001943:Breast Neoplasms / Q000188:drug therapy / Q000235:genetics*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects / Q000235:genetics; D002869:Chromosome Aberrations / Q000187:drug effects; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D005260:Female; D006657:Histones / Q000378:metabolism; D006801:Humans; D010766:Phosphorylation / Q000187:drug effects; D011123:Polyploidy; D047428:Protein Kinase Inhibitors / Q000494:pharmacology* / Q000633:toxicity; D011728:Pyridones / Q000494:pharmacology* / Q000633:toxicity; D020794:Receptor Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics; D008941:Spindle Apparatus / Q000187:drug effects / Q000378:metabolism
chemical_list: D000631:Aminopyridines; D006657:Histones; C550356:N-(4-(2-amino-3-chloropyridin-4-yloxy)-3-fluorophenyl)-4-ethoxy-1-(4-fluorophenyl)-2-oxo-1,2-dihydropyridine-3-carboxamide; D047428:Protein Kinase Inhibitors; D011728:Pyridones; C080835:RON protein; D020794:Receptor Protein-Tyrosine Kinases; D064107:Aurora Kinase B