Triple-negative breast cancer cell line sensitivity to englerin A identifies a new, targetable subtype

Corena V. Grant, Chase M. Carver, Shayne D. Hastings, Karthik Ramachandran, Madesh Muniswamy, April L. Risinger, John A. Beutler, Susan L. Mooberry

Research output: Contribution to journalArticle

Abstract

Purpose: Triple-negative breast cancers (TNBCs) represent a heterogeneous group of tumors. The lack of targeted therapies combined with the inherently aggressive nature of TNBCs results in a higher relapse rate and poorer overall survival. We evaluated the heterogeneity of TNBC cell lines for TRPC channel expression and sensitivity to cation-disrupting drugs. Methods: The TRPC1/4/5 agonist englerin A was used to identify a group of TNBC cell lines sensitive to TRPC1/4/5 activation and intracellular cation disruption. Quantitative RT-PCR, the sulforhodamine B assay, pharmacological inhibition, and siRNA-mediated knockdown approaches were employed. Epifluorescence imaging was performed to measure intracellular Ca2+ and Na+ levels. Mitochondrial membrane potential changes were monitored by confocal imaging. Results: BT-549 and Hs578T cells express high levels of TRPC4 and TRPC1/4, respectively, and are exquisitely, 2000- and 430-fold, more sensitive to englerin A than other TNBC cell lines. While englerin A caused a slow Na+ and nominal Ca2+ accumulation in Hs578T cells, it elicited rapid increases in cytosolic Ca2+ levels that triggered mitochondrial depolarization in BT-549 cells. Interestingly, BT-549 and Hs578T cells were also more sensitive to digoxin as compared to other TNBC cell lines. Collectively, these data reveal TRPC1/4 channels as potential biomarkers of TNBC cell lines with dysfunctional mechanisms of cation homeostasis and therefore sensitivity to cardiac glycosides. Conclusions: The sensitivity of BT-549 and Hs578T cells to englerin A and digoxin suggests a subset of TNBCs are highly susceptible to cation disruption and encourages investigation of TRPC1 and TRPC4 as potential new biomarkers of sensitivity to cardiac glycosides.

Original languageEnglish (US)
Pages (from-to)345-355
Number of pages11
JournalBreast Cancer Research and Treatment
Volume177
Issue number2
DOIs
StatePublished - Sep 15 2019

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Keywords

  • Cation disruption
  • Digoxin
  • Englerin A
  • TRPC1/4/5
  • Triple-negative breast cancer

ASJC Scopus subject areas

  • Oncology
  • Cancer Research

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