PLK4 is a determinant of temozolomide sensitivity through phosphorylation of IKBKE in glioblastoma.

Despite the clinical success of temozolomide (TMZ), its sensitivity remains a major challenge in glioblastoma (GBM). Here, we show that PLK4 affects TMZ sensitivity by regulating the IKBKE/NF-κB axis. The mRNA level of PLK4 was significantly associated with glioma grade progression and inversely correlated with overall survival (OS) in patients with high-grade gliomas (HGG). Further analyses indicated that GBM patients with low PLK4 expression levels gained greater survival benefits from chemotherapy than did those with high PLK4 expression. In GBM cells, TMZ sensitivity was decreased by ectopic expression of PLK4 and enhanced by depletion of PLK4. In the GBM mice model, inhibiting PLK4 in combination with chemotherapy slowed tumor growth and provided a significant survival benefit. Furthermore, PLK4 interacted with and phosphorylated IKBKE, leading to an increase in NF-κB transcriptional activity and anti-apoptosis. Notably, the PLK4 inhibitor CFI400945, which is currently in clinical trials, had a synergistic effect with TMZ, increasing TMZ sensitivity in xenografts from patient-derived primary GBMs. Our work describes the PLK4-IKBKE signaling axis that influences GBM proliferation and chemosensitivity, and can enhance the anti-tumor effects of chemotherapy via therapeutic targeting.