Withaferin A suppresses breast cancer cell proliferation by inhibition of the two-pore domain potassium (K2P9) channel TASK-3

Biomed Pharmacother. 2020 Sep:129:110383. doi: 10.1016/j.biopha.2020.110383. Epub 2020 Jun 17.

Abstract

Withaferin A (WFA), a C5,C6-epoxy steroidal lactone isolated from the medicinal plant Withania somnifera (L.) Dunal, inhibits growth of tumor cells in different cancer types. However, the mechanisms underlying the effect of WFA on tumor cells are not fully understood. In the present study, we evaluated the blockade of TASK-3 channels by WFA in TASK-3-expressing HEK-293 cells. Explore if the WFA-mediated TASK-3 blockade can be used as a pharmacological tool to decrease the cell viability in cancer cells. A combination of functional experiments (patch-clamp, gene downregulation, overexpression and pharmacological inhibition) and molecular docking analysis were used to get insights into the mechanism by which the inhibition of TASK-3 by WFA affects the growth and viability of cancer cells. Withaferin A was found to inhibit the activity of TASK-3 channels. The inhibitory effect of Withaferin A on TASK-3 potassium currents was dose-dependent and independent of voltage. Molecular modeling studies identified putative WFA-binding sites in TASK-3 channel involved the channel blockade. In agreements with the molecular modeling predictions, mutation of residues F125 to A (F125A), L197 to V (L197 V) and the double mutant F125A-L197 V markedly decreased the WFA-induced inhibition of TASK-3. Finally, the cytotoxic effect of WFA was tested in MDA-MB-231 human breast cancer cells transfected with TASK-3 or shRNA that decreases TASK-3 expression. Together, our results show that the cytotoxic effect of WFA on fully transformed MDA-MB-231 cells depends on the expression of TASK-3. Herein, we also provide insights into the mechanism of TASK-3 inhibition by WFA.

Keywords: Breast cancer; TASK-3; Two-pore domain channel; Withaferin A.

MeSH terms

  • Antineoplastic Agents, Phytogenic / metabolism
  • Antineoplastic Agents, Phytogenic / pharmacology*
  • Binding Sites
  • Breast Neoplasms / drug therapy*
  • Breast Neoplasms / genetics
  • Breast Neoplasms / metabolism
  • Breast Neoplasms / pathology
  • Cell Line, Tumor
  • Cell Proliferation / drug effects*
  • Female
  • Gene Expression Regulation, Neoplastic
  • HEK293 Cells
  • Humans
  • Membrane Potentials
  • Potassium Channel Blockers / metabolism
  • Potassium Channel Blockers / pharmacology*
  • Potassium Channels, Tandem Pore Domain / antagonists & inhibitors*
  • Potassium Channels, Tandem Pore Domain / genetics
  • Potassium Channels, Tandem Pore Domain / metabolism
  • Protein Binding
  • Signal Transduction
  • Withanolides / metabolism
  • Withanolides / pharmacology*

Substances

  • Antineoplastic Agents, Phytogenic
  • KCNK9 protein, human
  • Potassium Channel Blockers
  • Potassium Channels, Tandem Pore Domain
  • Withanolides
  • withaferin A