Pyoluteorin induces cell cycle arrest and apoptosis in human triple-negative breast cancer cells MDA-MB-231.

Objectives: To screen the cytotoxic activity of six secondary metabolites isolated from soil fungus Aspergillus niger. Importantly, to investigate the mechanism that pyoluteorin induced human triple-negative breast cancer MDA-MB-231 cells apoptosis in vitro.
Methods: The cell viability assay was tested with CTG assay. Cell cycle, apoptosis and intracellular reactive oxygen species (ROS) production assay were tested with flow cytometry. Additionally, intracellular ROS production assay and mitochondrial membrane potential assay were determined with laser scanning confocal microscopy. The expression of apoptosis-related proteins was determined with Western blot.
Key Findings: Pyoluteorin displayed significantly selective cytotoxicity against human triple-negative breast cancer MDA-MB-231 cells (IC ₅₀  = 0.97 µm) with low toxicity against human breast epithelial cell MCF-10A. It was found that pyoluteorin could arrest MDA-MB-231 cells cycle at G ₂ /M phase and induce cell apoptosis. Further experiments demonstrated that the apoptosis-inducing effect of pyoluteorin was related to reduction of mitochondrial membrane potential, accumulation of ROS and change of apoptosis-related protein expressions.
Conclusion: Our studies revealed that pyoluteorin had potent proliferation inhibition against MDA-MB-231 cells through arresting cell cycle at G ₂ /M phase and inducing caspase-3-dependent apoptosis by mitochondrial pathway, implying that pyoluteorin may be a potential lead compound for drug discovery of human triple-negative breast cancer.
(© 2020 Royal Pharmaceutical Society.)