Mutant p53 oncogenic functions are sustained by Plk2 kinase through an autoregulatory feedback loop

Area of Science:

• Molecular Biology
• Oncology
• Biochemistry

Background:

• Aberrant kinase activation is crucial in tumor progression and treatment response.
• Mutant p53 proteins often contribute to oncogenesis.
• Understanding regulatory networks involving kinases and tumor suppressors is vital for cancer therapy.

Purpose of the Study:

• To investigate the functional relationship between Polo-like kinase-2 (Plk2) and mutant p53 in cancer.
• To elucidate the role of this interaction in tumor growth, phenotype maintenance, and chemo-resistance.
• To identify a novel therapeutic target within this regulatory network.

Main Methods:

• Investigated the interaction and phosphorylation of mutant p53 by Plk2.
• Assessed the impact of this interaction on p53 binding to p300 and transcriptional activity.
• Utilized siRNA-mediated knockdown of Plk2 and mutant p53 to evaluate their roles in tumor cell proliferation and chemo-resistance.

Main Results:

• Plk2 directly binds and phosphorylates mutant p53, enhancing its oncogenic activity.
• Phosphorylated mutant p53 exhibits increased binding to p300, boosting its transcriptional activity.
• Plk2 gene expression is regulated by both wild-type and mutant p53, influencing cell proliferation and chemo-resistance.
• Knockdown of Plk2 or mutant p53 significantly reduces tumor cell growth and chemo-resistance.

Conclusions:

• A novel oncogenic auto-regulatory feedback loop involving Plk2 and mutant p53 has been identified.
• This Plk2-mutant p53 network plays a critical role in promoting tumor cell proliferation and chemo-resistance.
• Targeting this network, particularly in response to DNA damage, may offer new therapeutic strategies for human cancers.