VRK1 as a synthetic lethal target in VRK2 promoter–methylated cancers of the nervous system
Jonathan So, … , Mariella G. Filbin, William C. Hahn
Jonathan So, … , Mariella G. Filbin, William C. Hahn
Published August 30, 2022
Citation Information: JCI Insight. 2022;7(19):e158755. https://doi.org/10.1172/jci.insight.158755.
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Research Article Oncology

VRK1 as a synthetic lethal target in VRK2 promoter–methylated cancers of the nervous system

Abstract

Collateral lethality occurs when loss of a gene/protein renders cancer cells dependent on its remaining paralog. Combining genome-scale CRISPR/Cas9 loss-of-function screens with RNA sequencing in over 900 cancer cell lines, we found that cancers of nervous system lineage, including adult and pediatric gliomas and neuroblastomas, required the nuclear kinase vaccinia-related kinase 1 (VRK1) for their survival in vivo. VRK1 dependency was inversely correlated with expression of its paralog VRK2. VRK2 knockout sensitized cells to VRK1 loss, and conversely, VRK2 overexpression increased cell fitness in the setting of VRK1 loss. DNA methylation of the VRK2 promoter was associated with low VRK2 expression in human neuroblastomas and adult and pediatric gliomas. Mechanistically, depletion of VRK1 reduced barrier-to-autointegration factor phosphorylation during mitosis, resulting in DNA damage and apoptosis. Together, these studies identify VRK1 as a synthetic lethal target in VRK2 promoter–methylated adult and pediatric gliomas and neuroblastomas.

Authors

Jonathan So, Nathaniel W. Mabe, Bernhard Englinger, Kin-Hoe Chow, Sydney M. Moyer, Smitha Yerrum, Maria C. Trissal, Joana G. Marques, Jason J. Kwon, Brian Shim, Sangita Pal, Eshini Panditharatna, Thomas Quinn, Daniel A. Schaefer, Daeun Jeong, David L. Mayhew, Justin Hwang, Rameen Beroukhim, Keith L. Ligon, Kimberly Stegmaier, Mariella G. Filbin, William C. Hahn

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Figure 6

VRK1 is a dependency in vivo.

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VRK1 is a dependency in vivo. (A) Left panel: Immunoblot of VRK1 followi...
(A) Left panel: Immunoblot of VRK1 following tamoxifen-induced expression of sgVRK1 in LN443 cells. Right panel: Clonogenic assay in LN443 cells 14 days following tamoxifen-induced KO of VRK1. (B) Schematic of the in vivo xenograft experiment. The SF295 GBM cell line was transduced with Cas9, Cre-ERT2, and Switch-ON guide plasmids and implanted in NSG mouse flanks. When the tumors reached a prespecified size (200 mm3), the mice were treated with tamoxifen. When the tumor size reached approximately 500 mm3 or 40 days following treatment, the mice were euthanized. (C) Tumor volume measurements over time of the flank xenografts. * represents injection of tamoxifen or corn oil vehicle control. (D) Left panel: representative H&E sections of tumors taken from xenografted mice, 7 days following treatment with tamoxifen or vehicle control (scale bar: 50 μm). Sections were stained with an antibody against phospho-H2AX. Right panel: quantitation of number of phospho-H2AX–positive cells per 0.5 mm2 in flank xenografts following tamoxifen or vehicle treatment (n = 4 fields; mean ± SD) (*P < 0.05; 2-tailed Student’s t test). (E) Representative bioluminescence imaging of intracranial xenografts of primary DMG neurospheres with doxycycline-inducible control versus VRK1 targeting guides taken 30 days after doxycycline induction. (F) Quantification of bioluminescence images from E (sgCtrl vs. sgVRK1, P = 0.08). (G) Kaplan-Meier survival curves showing overall survival for mice injected with sgCtrl or sgVRK1 DMG neurospheres into the cranium. Significance was determined by log-rank test (sgCtrl vs. sgVRK1, P = 0.10).