PLK1 Induces Chromosomal Instability and Overrides Cell-Cycle Checkpoints to Drive Tumorigenesis

Area of Science:

• Molecular Biology
• Cancer Biology
• Genetics

Background:

• Polo-like kinase 1 (PLK1) is a crucial regulator of the cell cycle.
• PLK1 is frequently overexpressed in numerous human cancers, suggesting a role in tumorigenesis.

Purpose of the Study:

• To investigate whether PLK1 overexpression drives tumor development.
• To elucidate the mechanisms by which elevated PLK1 levels contribute to cancer progression.

Main Methods:

• Generation of transgenic mouse models with ubiquitous increased PLK1 expression.
• Analysis of mitotic and cytokinesis defects, centrosome abnormalities, and cell-cycle checkpoint function.
• Assessment of chromosomal instability (CIN), aneuploidy, and tumor formation in vivo.
• Correlation of PLK1 expression with genome-wide copy-number alterations in human cancers.

Main Results:

• High PLK1 levels promoted the development of spontaneous tumors across various types.
• Increased PLK1 caused mitotic and cytokinesis defects, leading to supernumerary centrosomes and compromised cell-cycle checkpoints.
• PLK1 overexpression resulted in accumulated chromosomal instability (CIN), aneuploidy, and subsequent tumor formation.
• Clinical data showed a positive association between higher PLK1 expression and increased genome-wide copy-number alterations in human cancers.

Conclusions:

• Aberrant PLK1 expression is a driving force for CIN and tumorigenesis in vivo.
• PLK1 acts as a potent proto-oncogene and a chromosomal instability gene.
• These findings identify PLK1 as a potential therapeutic target for CIN-positive cancers.