title: A kinase inhibitor screen identifies Mcl-1 and Aurora kinase A as novel treatment targets in antiestrogen-resistant breast cancer cells.
abstract: Antiestrogen resistance is a major problem in breast cancer treatment. Therefore, the search for new therapeutic targets and biomarkers for antiestrogen resistance is crucial. In this study, we performed a kinase inhibitor screen on antiestrogen responsive MCF-7 cells and a panel of MCF-7-derived tamoxifen- and fulvestrant-resistant cell lines. Our focus was to identify common and distinct molecular mechanisms involved in tamoxifen- and fulvestrant-resistant cell growth. We identified 18 inhibitors, of which the majority was common for both tamoxifen- and fulvestrant-resistant cell lines. Two compounds, WP1130 and JNJ-7706621, exhibiting prominent preferential growth inhibition of antiestrogen-resistant cell lines, were selected for further studies. WP1130, a deubiquitinase inhibitor, induced caspase-mediated cell death in both tamoxifen- and fulvestrant-resistant cell lines by destabilization of the anti-apoptotic protein Mcl-1. Mcl-1 expression was found upregulated in the antiestrogen-resistant cell lines and depletion of Mcl-1 in resistant cells caused decreased viability. JNJ-7706621, a dual Aurora kinase and cyclin-dependent kinase inhibitor, specifically inhibited growth and caused G2 phase cell cycle arrest of the tamoxifen-resistant cell lines. Knockdown studies showed that Aurora kinase A is essential for growth of the tamoxifen-resistant cells and inhibition of Aurora kinase A resensitized tamoxifen-resistant cells to tamoxifen treatment. Preferential growth inhibition by WP1130 and JNJ-7706621 was also found in T47D-derived tamoxifen-resistant cell lines, pointing at Mcl-1 and Aurora kinase A as potential treatment targets. In addition, tumor samples from 244 estrogen receptor-positive breast cancer patients treated with adjuvant tamoxifen showed that higher expression level of Aurora kinase A was significantly associated with shorter disease-free and overall survival, demonstrating the potential of Aurora kinase A as a biomarker for tamoxifen resistance.
authors.affiliation: Breast Cancer Group, Unit of Cell Death and Metabolism, Danish Cancer Society Research Center, Copenhagen, Denmark.
authors.forename: S
authors.initials: S
authors.lastname: Thrane
authors.affiliation: Breast Cancer Group, Unit of Cell Death and Metabolism, Danish Cancer Society Research Center, Copenhagen, Denmark.
authors.forename: A M
authors.initials: AM
authors.lastname: Pedersen
authors.affiliation: Breast Cancer Group, Unit of Cell Death and Metabolism, Danish Cancer Society Research Center, Copenhagen, Denmark.
authors.forename: M B H
authors.initials: MB
authors.lastname: Thomsen
authors.affiliation: Breast Cancer Group, Unit of Cell Death and Metabolism, Danish Cancer Society Research Center, Copenhagen, Denmark.
authors.forename: T
authors.initials: T
authors.lastname: Kirkegaard
authors.affiliation: Department of Pathology, Herlev Hospital, Herlev, Denmark.
authors.forename: B B
authors.initials: BB
authors.lastname: Rasmussen
authors.affiliation: Statistics, Bioinformatics and Registry, Danish Cancer Society Research Center, Copenhagen, Denmark.
authors.forename: A K
authors.initials: AK
authors.lastname: Duun-Henriksen
authors.affiliation: Department of Pathology, Slagelse Hospital, Slagelse, Denmark.
authors.forename: A V
authors.initials: AV
authors.lastname: Lænkholm
authors.affiliation: Department of Clinical Pathology, Odense University Hospital, Odense, Denmark.
authors.forename: M
authors.initials: M
authors.lastname: Bak
authors.affiliation: Breast Cancer Group, Unit of Cell Death and Metabolism, Danish Cancer Society Research Center, Copenhagen, Denmark.
authors.forename: A E
authors.initials: AE
authors.lastname: Lykkesfeldt
authors.affiliation: Breast Cancer Group, Unit of Cell Death and Metabolism, Danish Cancer Society Research Center, Copenhagen, Denmark.
authors.forename: C W
authors.initials: CW
authors.lastname: Yde
mesh_terms: D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D064096:Aurora Kinase A / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D014408:Biomarkers, Tumor / Q000235:genetics / Q000378:metabolism; D001943:Breast Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism; D020169:Caspases / Q000378:metabolism; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects / Q000235:genetics; D003487:Cyanoacrylates / Q000494:pharmacology; D019008:Drug Resistance, Neoplasm / Q000187:drug effects* / Q000235:genetics; D004354:Drug Screening Assays, Antitumor; D004958:Estradiol / Q000031:analogs & derivatives / Q000494:pharmacology; D004965:Estrogen Antagonists / Q000494:pharmacology*; D000077267:Fulvestrant; D059565:G2 Phase Cell Cycle Checkpoints / Q000187:drug effects / Q000235:genetics; D006801:Humans; D061986:MCF-7 Cells; D064549:Myeloid Cell Leukemia Sequence 1 Protein / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D011725:Pyridines / Q000494:pharmacology; D034622:RNA Interference; D011960:Receptors, Estrogen / Q000378:metabolism; D016019:Survival Analysis; D013629:Tamoxifen / Q000494:pharmacology; D014230:Triazoles / Q000494:pharmacology
chemical_list: D014408:Biomarkers, Tumor; D003487:Cyanoacrylates; D004965:Estrogen Antagonists; C506121:JNJ-7706621; C579095:MCL1 protein, human; D064549:Myeloid Cell Leukemia Sequence 1 Protein; D047428:Protein Kinase Inhibitors; D011725:Pyridines; D011960:Receptors, Estrogen; D014230:Triazoles; C519751:degrasyn; D013629:Tamoxifen; D000077267:Fulvestrant; D004958:Estradiol; D064096:Aurora Kinase A; D020169:Caspases