PLK4 (Polo-like kinase 4)

Class

Small molecule kinase inhibitor

Pathway

Centriole duplication / mitotic regulation - induces mitotic catastrophe and cell death

PLK4 (Polo-like kinase 4) is an enzyme that controls centriole duplication, the process by which cells build the paired structures that organize the mitotic spindle during cell division. Under normal conditions, each cell duplicates its centrosome exactly once per cycle, and PLK4 activity is the master switch that enforces this precise timing. Many cancer cells show abnormal centrosome numbers, a feature linked to chromosomal instability and tumor progression. Because dividing cells depend heavily on correctly balanced centriole numbers, pharmacologically inhibiting PLK4 can push cancer cells—many of which already operate with fragile mitotic machinery—into further spindle errors, culminating in a process called mitotic catastrophe, where cells with unresolved chromosomal damage die during or after an aberrant division. This approach is being explored broadly across solid tumors and hematologic malignancies where centrosome abnormalities and rapid proliferation are common features. The therapeutic rationale rests on exploiting a vulnerability specific to cells that are already dividing under stress, rather than targeting a mutated oncogene directly, making PLK4 inhibition a mechanistically distinct approach to disrupting cancer cell division.