Cyclin E modulates vulnerability to CDC7 kinase inhibition

Area of Science:

• Oncology
• Molecular Biology
• Cancer Therapeutics

Background:

• CCNE1 (cyclin E) amplification/overexpression is common in triple-negative breast cancer (TNBC).
• Cyclin E overexpression causes replication stress and is linked to poor patient outcomes.
• Targeting cyclin E-induced replication stress presents a therapeutic opportunity for TNBC.

Purpose of the Study:

• To investigate the efficacy of CDC7 kinase inhibition in TNBC cells with CCNE1 overexpression.
• To identify resistance mechanisms and synergistic targets for CDC7 inhibition in TNBC.

Main Methods:

• Treatment of TNBC cells with CCNE1 overexpression using CDC7 inhibitors.
• Assessment of cell proliferation, colony formation, and DNA content.
• CRISPR screening to identify resistance genes.
• Combination therapy with CDC7 and CDK8 inhibitors in vitro and in vivo.

Main Results:

• CCNE1 overexpression sensitized TNBC cells to CDC7 inhibition, reducing proliferation and colony formation.
• CDC7 inhibition caused replication timing delays and polyploidy (≥4N DNA content).
• CDK8 was identified as a resistance factor to CDC7 inhibition; combined inhibition synergistically reduced proliferation and tumor growth.

Conclusions:

• TNBC cells overexpressing cyclin E are uniquely vulnerable to CDC7 kinase inhibition.
• Combined inhibition of CDC7 and CDK8 demonstrates significant therapeutic synergy against TNBC.
• This combination therapy warrants further investigation for clinical application in TNBC treatment.