Ouabain and chloroquine trigger senolysis of BRAF-V600E-induced senescent cells by targeting autophagy

Area of Science:

• Oncology
• Cellular Senescence
• Pharmacology

Background:

• BRAF-V600E expression induces oncogene-induced senescence, a state linked to cancer development, particularly melanoma.
• Senescent cells contribute to aging and cancer progression, making senolytic therapies a focus of research.

Purpose of the Study:

• To investigate cardioglycosides, specifically ouabain, as senolytic agents against BRAF-senescence.
• To elucidate the molecular mechanisms underlying ouabain-mediated senolysis in BRAF-senescent cells.
• To identify novel senolytic strategies targeting the endoplasmic reticulum stress-autophagy pathway.

Main Methods:

• Utilized BRAF-V600E-induced senescence models.
• Investigated the role of the Na,K-ATPase pump in ouabain senolysis via knockdown and ion supplementation experiments.
• Analyzed signal transduction pathways (Src, p38, Akt, Erk) and their involvement in cell death.
• Assessed the impact of BRAF-V600E on ER stress and autophagy.
• Evaluated chloroquine as a potential senolytic agent.

Main Results:

• Ouabain demonstrated potent senolytic activity in BRAF-senescent cells, mediated by the Na,K-ATPase pump.
• Senolysis required both ion transport inhibition and signal transduction initiated by ouabain binding to the pump.
• BRAF-V600E expression elevated ER stress and autophagy, sensitizing cells to ouabain.
• Ouabain inhibited autophagy flux, which was reversible with signaling inhibitors.
• Chloroquine was identified as a novel senolytic for BRAF senescence.

Conclusions:

• Cardioglycosides are effective senolytics in BRAF senescence via Na,K-ATPase-mediated signaling.
• The endoplasmic reticulum stress-autophagy pathway represents a novel vulnerability in BRAF-senescent cells.
• Targeting this pathway offers potential for developing new senolytic therapies against BRAF-driven cancers.