Cyclin E1 and RTK/RAS signaling drive CDK inhibitor resistance via activation of E2F and ETS

Area of Science:

• Oncology
• Molecular Biology
• Cancer Genomics

Background:

• High-grade serous ovarian cancer (HGSOC) presents significant therapeutic challenges due to genomic complexity, heterogeneity, and acquired chemoresistance.
• Cyclin-dependent kinase inhibitors (CDKi) targeting the retinoblastoma (RB) signaling network are established treatments for various cancers, but their specific application in HGSOC requires further investigation.
• Understanding mechanisms of response and resistance to different classes of CDKi is crucial for developing targeted therapies for HGSOC.

Purpose of the Study:

• To compare mechanisms of response and resistance to CDK4/6 and CDK2 inhibitors in HGSOC.
• To identify genetic alterations and signaling pathways associated with CDKi resistance.
• To evaluate the potential of CDKi in combination with chemotherapy for HGSOC treatment.

Main Methods:

• Comparative analysis of three distinct cyclin-dependent kinase inhibitors (CDKi) targeting CDK4/6 or CDK2.
• Investigation of genetic alterations including CCNE1 gain and RB1 loss.
• Assessment of receptor tyrosine kinase (RTK) and RAS signaling pathways.
• Mechanistic studies involving ETS factors and their role in cell cycle progression.
• Evaluation of CDK2 inhibitor sensitivity in relation to cyclin E1 and RAS signaling in ovarian cancer cells.

Main Results:

• CCNE1 gain and RB1 loss were identified as key mechanisms of resistance to CDK4/6 inhibitors.
• Receptor tyrosine kinase (RTK) and RAS signaling pathways were associated with resistance to CDK2 inhibitors.
• ETS factors were found to mediate RTK/RAS signaling and cooperate with E2F in driving cell cycle progression.
• CDK2 inhibition demonstrated the ability to sensitize cyclin E1-driven ovarian cancer cells, but not RAS-driven cells, to platinum-based chemotherapy.

Conclusions:

• This study elucidates distinct resistance mechanisms to CDK4/6 and CDK2 inhibitors in HGSOC.
• Identifying specific signaling pathways (RTK/RAS) and genetic alterations (CCNE1, RB1) provides a basis for predicting CDKi response.
• The findings support a rational approach for integrating CDKi into HGSOC treatment regimens, potentially enhancing efficacy when combined with chemotherapy based on specific cellular drivers.