DNA-PK/Chk2 induces centrosome amplification during prolonged replication stress

Area of Science:

• Cell Biology
• Molecular Oncology
• Genomic Instability

Background:

• Antineoplastic drugs like hydroxyurea (HU) can induce replication stress and centrosome amplification.
• Centrosome amplification is linked to genomic instability and increased tumor malignancy.
• The precise mechanisms underlying HU-induced centrosome amplification remain unclear.

Purpose of the Study:

• To investigate the roles of ATM, ATR, and DNA-PK in HU-induced centrosome amplification.
• To elucidate the signaling pathways involved in this process.

Main Methods:

• Utilized hydroxyurea (HU) treatment in cell culture models.
• Employed gene depletion techniques (e.g., DNA-PKcs, ATM, ATR, Chk2).
• Assessed centrosome amplification, genomic instability, and protein phosphorylation (e.g., ATM, Chk2).

Main Results:

• DNA-dependent protein kinase catalytic subunit (DNA-PKcs) depletion inhibited HU-induced centrosome amplification.
• ATM/ATR inactivation led to aneuploidy and cell death, not inhibition of centrosome amplification.
• DNA-PKcs depletion abrogated ATM phosphorylation, indicating DNA-PK is upstream of ATM activation.
• DNA-PKcs depletion reduced Chk1 and Chk2 activation; Chk2 depletion blocked centrosome amplification.
• Chk2 phosphorylation at Thr68 was observed on amplified centrioles.

Conclusions:

• DNA-PK/Chk2 signaling pathway is crucial for hydroxyurea-induced centrosome amplification.
• This pathway contributes to genomic instability and potentially tumor recurrence after chemotherapy.
• Targeting DNA-PK/Chk2 may offer strategies to overcome chemotherapy resistance.