The NF-κB Pathway Promotes Tamoxifen Tolerance and Disease Recurrence in Estrogen Receptor-Positive Breast Cancers

Mol Cancer Res. 2020 Jul;18(7):1018-1027. doi: 10.1158/1541-7786.MCR-19-1082. Epub 2020 Apr 3.

Abstract

The purpose of this study was to identify critical pathways promoting survival of tamoxifen-tolerant, estrogen receptor α positive (ER+) breast cancer cells, which contribute to therapy resistance and disease recurrence. Gene expression profiling and pathway analysis were performed in ER+ breast tumors of patients before and after neoadjuvant tamoxifen treatment and demonstrated activation of the NF-κB pathway and an enrichment of epithelial-to mesenchymal transition (EMT)/stemness features. Exposure of ER+ breast cancer cell lines to tamoxifen, in vitro and in vivo, gives rise to a tamoxifen-tolerant population with similar NF-κB activity and EMT/stemness characteristics. Small-molecule inhibitors and CRISPR/Cas9 knockout were used to assess the role of the NF-κB pathway and demonstrated that survival of tamoxifen-tolerant cells requires NF-κB activity. Moreover, this pathway was essential for tumor recurrence following tamoxifen withdrawal. These findings establish that elevated NF-κB activity is observed in breast cancer cell lines under selective pressure with tamoxifen in vitro and in vivo, as well as in patient tumors treated with neoadjuvant tamoxifen therapy. This pathway is essential for survival and regrowth of tamoxifen-tolerant cells, and, as such, NF-κB inhibition offers a promising approach to prevent recurrence of ER+ tumors following tamoxifen exposure. IMPLICATIONS: Understanding initial changes that enable survival of tamoxifen-tolerant cells, as mediated by NF-κB pathway, may translate into therapeutic interventions to prevent resistance and relapse, which remain major causes of breast cancer lethality.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Breast Neoplasms / drug therapy
  • Breast Neoplasms / genetics
  • Breast Neoplasms / metabolism
  • Breast Neoplasms / pathology*
  • Drug Resistance, Neoplasm*
  • Epithelial-Mesenchymal Transition / drug effects
  • Estrogen Receptor alpha / metabolism*
  • Female
  • Gene Expression Profiling / methods
  • Gene Expression Regulation, Neoplastic / drug effects
  • Gene Regulatory Networks / drug effects*
  • Humans
  • MCF-7 Cells
  • Mice
  • NF-kappa B / metabolism
  • Neoplasm Recurrence, Local / drug therapy
  • Neoplasm Recurrence, Local / genetics
  • Neoplasm Recurrence, Local / metabolism
  • Neoplasm Recurrence, Local / pathology*
  • Neoplasm Transplantation
  • Signal Transduction / drug effects
  • Tamoxifen / administration & dosage*
  • Tamoxifen / pharmacology

Substances

  • ESR1 protein, human
  • Estrogen Receptor alpha
  • NF-kappa B
  • Tamoxifen