Data from VRK1 Is a Synthetic–Lethal Target in VRK2-Deficient Glioblastoma

Abstract

<div>Abstract<p>Synthetic lethality is a genetic interaction that results in cell death when two genetic deficiencies co-occur but not when either deficiency occurs alone, which can be co-opted for cancer therapeutics. Pairs of paralog genes are among the most straightforward potential synthetic–lethal interactions by virtue of their redundant functions. Here, we demonstrate a paralog-based synthetic lethality by targeting vaccinia-related kinase 1 (VRK1) in glioblastoma (GBM) deficient of VRK2, which is silenced by promoter methylation in approximately two thirds of GBM. Genetic knockdown of VRK1 in VRK2-null or <i>VRK2</i>-methylated cells resulted in decreased activity of the downstream substrate barrier to autointegration factor (BAF), a regulator of post-mitotic nuclear envelope formation. Reduced BAF activity following VRK1 knockdown caused nuclear lobulation, blebbing, and micronucleation, which subsequently resulted in G<sub>2</sub>–M arrest and DNA damage. The VRK1–VRK2 synthetic–lethal interaction was dependent on VRK1 kinase activity and was rescued by ectopic expression of VRK2. In <i>VRK2</i>-methylated GBM cell line–derived xenograft and patient-derived xenograft models, knockdown of VRK1 led to robust tumor growth inhibition. These results indicate that inhibiting VRK1 kinase activity could be a viable therapeutic strategy in <i>VRK2</i>-methylated GBM.</p>Significance:<p>A paralog synthetic–lethal interaction between VRK1 and VRK2 sensitizes <i>VRK2</i>-methylated glioblastoma to perturbation of VRK1 kinase activity, supporting VRK1 as a drug discovery target in this disease.</p></div>