The Vacuolar ATPase a2-subunit regulates Notch signaling in triple-negative breast cancer cells

Area of Science:

• Molecular Biology
• Oncology
• Cell Biology

Background:

• Triple Negative Breast Cancer (TNBC) lacks targeted therapies and has a poor prognosis.
• Notch signaling is implicated in breast cancer, but its regulation in TNBC is unclear.
• Vacuolar ATPase (V-ATPase) is crucial for cancer cell invasiveness.

Purpose of the Study:

• To investigate the role of the V-ATPase a2-subunit isoform (a2V) in regulating Notch signaling in TNBC.
• To explore a2V as a potential therapeutic target for TNBC.

Main Methods:

• Confocal microscopy to determine a2V expression in breast cancer cells.
• Quantitative analysis of a2V and NOTCH1 expression in TNBC tissues and cell lines.
• RNA interference (siRNA) for a2V knockdown and V-ATPase inhibition using Bafilomycin A1 (Baf A1).
• Assessment of Notch1 Intracellular Domain (N1ICD) expression, autophagy markers (LC3B), and lysosomal markers (LAMP1).
• Cell migration assays and treatment with Baf A1 or anti-a2V neutralizing antibody.

Main Results:

• a2V was uniquely expressed on the plasma membrane of breast cancer cells and elevated in TNBC.
• a2V knockdown and V-ATPase inhibition enhanced Notch signaling by increasing N1ICD levels.
• V-ATPase inhibition disrupted autophagy and lysosomal acidification, blocking NICD degradation.
• Treatment with Baf A1 or anti-a2V antibody inhibited TNBC cell migration.

Conclusions:

• a2V regulates Notch signaling in TNBC via its role in endolysosomal acidification.
• a2V emerges as a potential therapeutic target for Triple Negative Breast Cancer.
• Targeting V-ATPase activity or a2V may offer a novel strategy for TNBC treatment.