Palbociclib resistance confers dependence on an FGFR-MAP kinase-mTOR-driven pathway in KRAS-mutant non-small cell...

Area of Science:

• Oncology
• Molecular Biology
• Cancer Research

Background:

• Cyclin-dependent kinase 4 (CDK4) is a potential therapeutic target in KRAS-mutant non-small cell lung cancer (NSCLC).
• Initial sensitivity to CDK4/6 inhibitors like palbociclib is observed in KRAS-mutant NSCLC, but acquired resistance is a significant clinical challenge.

Purpose of the Study:

• To investigate the mechanisms of acquired resistance to palbociclib in KRAS-mutant NSCLC.
• To identify potential therapeutic strategies to overcome palbociclib resistance in this cancer type.

Main Methods:

• Utilized KRAS-mutant NSCLC cell lines and a genetically-engineered mouse model.
• Assessed cellular responses to palbociclib, MEK inhibitors, and ERK inhibitors.
• Analyzed the expression of cell cycle proteins, signaling pathway components (ERK1/2, mTOR, FGFR1), and FGF ligands.

Main Results:

• KRAS-mutant NSCLC cell lines acquired resistance to palbociclib through increased expression of CDK6, D-type cyclins, and cyclin E, alongside elevated ERK1/2 activity.
• MEK inhibition reversed palbociclib resistance by reducing cell cycle mediator expression and activity.
• A signaling axis involving FGFR1, MAP kinase, and mTOR was identified as crucial for conferring palbociclib resistance.
• Combined palbociclib and MEK inhibitor treatment delayed resistance development in a mouse model.

Conclusions:

• Acquired resistance to palbociclib in KRAS-mutant NSCLC involves a feedback loop promoting cell cycle progression and MAP kinase pathway activation.
• Targeting the FGFR1-MAP kinase-mTOR pathway, particularly with MEK inhibitors, represents a promising strategy to overcome palbociclib resistance in NSCLC.
• CDK4/6 inhibition may potentiate dependence on the MAP kinase pathway, highlighting the rationale for combination therapies.