Cancer stem cell drugs target K-ras signaling in a stemness context

Area of Science:

• Oncology
• Molecular Biology
• Cell Biology

Background:

• Cancer stem cells (CSCs) drive tumor recurrence and treatment resistance.
• Salinomycin is a known CSC inhibitor, but its precise molecular target remains elusive.
• Understanding salinomycin's mechanism is crucial for developing novel anti-CSC therapies.

Purpose of the Study:

• To elucidate the primary mechanistic target of salinomycin.
• To identify novel CSC inhibitors targeting K-ras4B.
• To develop a predictive biomarker for salinomycin response.

Main Methods:

• Investigated salinomycin's effect on K-ras4B and H-ras membrane organization.
• Assessed the role of caveolae in drug sensitivity.
• Developed and validated a K-ras-associated gene expression signature.
• Screened for new CSC drugs using a K-ras-specific platform.

Main Results:

• Salinomycin specifically disrupts K-ras4B nanoscale membrane organization, independent of H-ras.
• Caveolae negatively regulate sensitivity to salinomycin.
• A novel gene signature predicts salinomycin response and correlates with higher mortality in TCGA tumor samples.
• Ophiobolin A and conglobatin A identified as potent CSC inhibitors, with ophiobolin A acting via K-ras4B/calmodulin inactivation.

Conclusions:

• Salinomycin's anti-CSC activity stems from specific interference with K-ras4B.
• The K-ras4B/calmodulin interaction is a selective target for inhibiting CSCs.
• This research provides a new therapeutic strategy and predictive biomarker for CSC-driven cancers.