API5 confers cancer stem cell-like properties through the FGF2-NANOG axis

Area of Science:

• Oncology
• Immunology
• Molecular Biology

Background:

• Tumor evolution under immune selection promotes immune resistance and cancer stem cell (CSC)-like phenotypes.
• Apoptosis inhibitor-5 (API5) is an immune escape factor, but its role in CSC properties is unclear.

Purpose of the Study:

• To investigate the functional association between API5 and CSC-like properties.
• To elucidate the molecular mechanisms linking API5, immune resistance, and CSC traits.
• To evaluate FGFR signaling blockade as a therapeutic strategy for API5-high cancers.

Main Methods:

• Assessed API5's role in conferring CSC-like properties (NANOG expression, CD44+ cells, sphere formation).
• Investigated the dependency on FGFR1 signaling, E2F1, and FGF2 expression.
• Identified the FGF2-NANOG molecular axis downstream of API5 signaling.
• Evaluated FGFR signaling blockade in API5-high human cancers.

Main Results:

• API5 confers CSC-like properties, including NANOG expression, CD44+ cell frequency, and sphere formation.
• API5-mediated CSC properties depend on FGFR1 signaling activated by E2F1-driven FGF2.
• The FGF2-NANOG axis is a downstream effector of API5 signaling, conserved in cervical cancer.
• FGFR signaling blockade effectively controls API5-high human cancers.

Conclusions:

• API5 plays a critical role in connecting tumor immune resistance with CSC-like properties.
• The API5-FGFR1-FGF2-NANOG pathway is a key mechanism driving aggressive cancer phenotypes.
• Targeting FGFR signaling presents a promising therapeutic approach for API5-positive refractory tumors.