PLK1 stabilizes a MYC-dependent kinase network in aggressive B cell lymphomas

Area of Science:

• Oncology
• Molecular Biology
• Proteomics

Background:

• Double-hit lymphoma (DHL) is characterized by aggressive disease due to concordant MYC and BCL-2 oncoprotein activation.
• Current treatments for DHL are often ineffective, highlighting the need for novel therapeutic targets.

Purpose of the Study:

• To identify essential regulators of the MYC-dependent kinome in DHL.
• To investigate the role of polo-like kinase-1 (PLK1) in DHL pathogenesis and its potential as a therapeutic target.

Main Methods:

• Activity-based proteomic profiling and drug screens were employed to identify key regulators in DHL.
• Expression levels of PLK1 and MYC were analyzed in DHL patient samples.
• The regulatory relationship between MYC and PLK1 was investigated.
• The effects of PLK1 inhibition on MYC and MCL-1 stability were assessed.
• Synergy between PLK1 inhibitors and BCL-2 antagonists was evaluated in vitro.

Main Results:

• PLK1 was identified as an essential regulator of the MYC-dependent kinome in DHL.
• High PLK1 expression in DHL correlated with MYC expression and predicted poor patient outcomes.
• A feed-forward circuit was established where PLK1 enhances MYC stability, and MYC induces PLK1 transcription.
• PLK1 inhibition led to the degradation of MYC and MCL-1.
• PLK1 inhibitors demonstrated synergistic effects with BCL-2 antagonists in inhibiting DHL cell growth and survival.

Conclusions:

• PLK1 plays a critical role in the aggressive behavior of DHL by regulating MYC stability and promoting cell survival.
• The identified MYC-PLK1 feed-forward circuit represents a key vulnerability in DHL.
• Targeting PLK1, particularly in combination with BCL-2 antagonists, holds significant promise for the clinical treatment of DHL.