A kinase inhibitor screen identifies Mcl-1 and Aurora kinase A as novel treatment targets in antiestrogen-resistant breast cancer cells

Oncogene. 2015 Aug 6;34(32):4199-210. doi: 10.1038/onc.2014.351. Epub 2014 Nov 3.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis / drug effects
  • Apoptosis / genetics
  • Aurora Kinase A / antagonists & inhibitors*
  • Aurora Kinase A / genetics
  • Aurora Kinase A / metabolism
  • Biomarkers, Tumor / genetics
  • Biomarkers, Tumor / metabolism
  • Breast Neoplasms / drug therapy
  • Breast Neoplasms / genetics
  • Breast Neoplasms / metabolism
  • Caspases / metabolism
  • Cell Line, Tumor
  • Cell Proliferation / drug effects
  • Cell Proliferation / genetics
  • Cyanoacrylates / pharmacology
  • Drug Resistance, Neoplasm / drug effects*
  • Drug Resistance, Neoplasm / genetics
  • Drug Screening Assays, Antitumor
  • Estradiol / analogs & derivatives
  • Estradiol / pharmacology
  • Estrogen Antagonists / pharmacology*
  • Fulvestrant
  • G2 Phase Cell Cycle Checkpoints / drug effects
  • G2 Phase Cell Cycle Checkpoints / genetics
  • Humans
  • MCF-7 Cells
  • Myeloid Cell Leukemia Sequence 1 Protein / antagonists & inhibitors*
  • Myeloid Cell Leukemia Sequence 1 Protein / genetics
  • Myeloid Cell Leukemia Sequence 1 Protein / metabolism
  • Protein Kinase Inhibitors / pharmacology*
  • Pyridines / pharmacology
  • RNA Interference
  • Receptors, Estrogen / metabolism
  • Survival Analysis
  • Tamoxifen / pharmacology
  • Triazoles / pharmacology


  • Biomarkers, Tumor
  • Cyanoacrylates
  • Estrogen Antagonists
  • JNJ-7706621
  • MCL1 protein, human
  • Myeloid Cell Leukemia Sequence 1 Protein
  • Protein Kinase Inhibitors
  • Pyridines
  • Receptors, Estrogen
  • Triazoles
  • degrasyn
  • Tamoxifen
  • Fulvestrant
  • Estradiol
  • Aurora Kinase A
  • Caspases