RIOK1 kinase activity is required for cell survival irrespective of MTAP status

Abstract

Genotype specific vulnerabilities of cancer cells constitute a promising strategy for the development of new therapeutics. Deletions of non-essential genes in tumors can generate unique vulnerabilities which could be exploited therapeutically. The MTAP gene is recurrently deleted in human cancers because of its chromosomal proximity to the tumor suppressor gene CDKN2A. Recent studies have uncovered an increased dependency of MTAP-deleted cancer cells on the function of a PRMT5 containing complex, including WDR77, PRMT5 and the kinase RIOK1. As RIOK1 kinase activity constitutes a potential therapeutic target, we wanted to test if MTAP deletion confers increased sensitivity to RIOK1 inhibition. Using CRISPR/Cas9-mediated genome engineering we generated analog sensitive alleles of RIOK1 in isogenic cell lines differing only by MTAP status. While we were able to independently confirm an increased dependency of MTAP-deleted cells on PRMT5, we did not detect a differential requirement for RIOK1 kinase activity between MTAP-proficient and deficient cells. Our results reveal that the kinase activity of RIOK1 is required for the survival of cancer cell lines irrespective of their MTAP status and cast doubt on the therapeutic exploitability of RIOK1 in the context of MTAP-deleted cancers.

SMARCA2-deficiency confers sensitivity to targeted inhibition of SMARCA4 in esophageal squamous cell carcinoma cell lines

“…To identify potential novel drug targets in ESCC, we applied domain-directed CRISPR-Cas9 screens 37 across ten ESCC cell lines. Stable Cas9-expressing cell lines were transduced with a sgRNA library consisting of >1300 sgRNAs targeting 179 epigenetic regulators 38 and negative selection of sgRNA-expressing cells was monitored by next-generation sequencing after 18 population doublings (Fig. 1A).…”

Inhibiting Arginine Methylation as a Tool to Investigate Cross-Talk with Methylation and Acetylation Post-Translational Modifications in a Glioblastoma Cell Line

“…Second, the present work relies on antibody specificity to draw the conclusion that ADMA cross-talks with SDMA and Lys acetylation. Although the α-ADMA, α-SDMA and α-Lys acetylation antibodies that we have used are state-of-the art in the field [26,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46], mass spectrometry-based proteomics approaches would complement our experiments and enable the identification of the proteins and mechanisms involved in PTM cross-talks. In particular, approaches to labelling Arg residues modified by methylation with 14 C and 13 CD 3 have been developed [47,48], and would prove very useful to identify the specific proteins undergoing methylation in further investigations of ADMA–SDMA cross-talk.…”

Genetic dependencies associated with transcription factor activities in human cancer cell lines

“…All CRISPR/Cas9 depletion assays were conducted as previously described previously 84 . Briefly, gRNAs were cloned into the lentiviral vector Lenti_gRNA GFP(LRG)_2.1T by GenScript Biotech.…”