Phenazine derivatives attenuate the stemness of breast cancer cells through triggering ferroptosis

Area of Science:

• Oncology
• Molecular Biology
• Drug Discovery

Background:

• Breast cancer stem cells (BCSCs) drive metastasis, chemoresistance, and recurrence.
• Targeting BCSCs is crucial for effective breast cancer treatment, yet no specific drugs are clinically available.
• Phenazine library screening offers a promising avenue for identifying novel anti-BCSC agents.

Purpose of the Study:

• To screen for small-molecule compounds targeting BCSCs from a pre-established phenazine library.
• To identify compounds that attenuate breast cancer cell stemness without affecting overall cell viability.
• To elucidate the mechanism by which these compounds inhibit BCSCs.

Main Methods:

• Phenazine library screening for compounds inhibiting BCSC stemness.
• Assessment of stemness markers (CD44+/CD24-), spheroid formation, and tumor-initiating capacity.
• In vitro and in vivo metastasis assays.
• Transcriptome sequencing to identify affected pathways.
• Mechanistic studies on ferroptosis induction and iron regulation.

Main Results:

• Three compounds (CPUL119, CPUL129, CPUL149) significantly reduced BCSC stemness and tumor-initiating capacity.
• These compounds suppressed breast cancer cell metastasis in vitro and in vivo.
• Transcriptome analysis revealed ferroptosis as a key upregulated pathway.
• Compounds were found to induce ferroptosis by accumulating lysosomal iron and regulating iron transport proteins (IRP2, TfR1, ferritin).
• Inhibiting ferroptosis reversed the anti-stemness effects of the compounds.

Conclusions:

• CPUL119, CPUL129, and CPUL149 specifically inhibit breast cancer stemness by inducing ferroptosis.
• These compounds represent potential therapeutic agents for breast cancer treatment by targeting BCSCs.
• The mechanism involves iron accumulation in lysosomes and regulation of iron metabolism proteins.