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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

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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 4

VRK1 loss is associated with nuclear envelope malformation.

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VRK1 loss is associated with nuclear envelope malformation.
(A) Nuclear ...
(A) Nuclear membrane morphology in the LN443 GBM cell line following exogenous VRK1 degradation by dTAGV-1 after 1 day. White arrows point to nuclear bridges. Blue arrow points to micro-nuclei. (B) Left: Quantitation of irregular nuclei, by LaminB1 staining, following VRK1 degradation as seen in A (n = 3 fields of >50 cells each; mean ± SD). Center: Quantitation of nuclear bridges following VRK1 degradation as seen in A (n = 3 fields of > 50 cells each; mean ± SD). Right: quantitation of irregular nuclei following VRK1 degradation in the NB-1 neuroblastoma cell line expressing GFP-BAF seen in Supplemental Figure 9D (n = 8 fields of >50 cells each; mean ± SD). (C) Quantitation of irregular nuclei, by LaminB1 staining, following KO of both VRK1 and VRK2 in SF172 as seen in Supplemental Figure 9A. (n = 4 fields of >50 cells each; mean ± SD.) (D) Immunoblot of phosphorylated BAF (S4) and total BAF following dTAGV-1 treatment in dTAG-VRK1-NB-1 cells (left panel) or KO of VRK1 with 2 independent sgRNAs in BT869Luci DMG neurospheres (right panel). Represents 2 independent experiments. (E) Left panel: Nuclear envelope morphology (Emerin-GFP) following doxycycline-induced expression of BAF mutants in LN443 GBM cell line after 3 days: wild-type (WT), S4A (nonphosphorylatable), S4D (phospho-mimetic). Right panel: Quantitation of nuclear bridging phenotype in LN443 cell lines expressing BAF mutants (n = 3; mean ± SD). (F) Live-cell, time-lapse experiment showing nuclear envelope morphology following VRK1 degradation in LN443 (dTAGV-1 addition at t = 0 hours). White arrows point to cells undergoing mitosis. Blue arrows point to chromatin bridges. Represents 2 independent experiments. Scale bars: 20 μm. *P < 0.05, **P < 0.001, ***P < 0.0001; significance was determined by 2-tailed Student’s t test (B) and 1-way ANOVA with Tukey’s test (C and E).

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