PT  - JOURNAL ARTICLE
AU  - Satu Pallasaho
AU  - Aishwarya Gondane
AU  - Damien Duveau
AU  - Craig Thomas
AU  - Massimo Loda
AU  - Harri M Itkonen
TI  - Compromised CDK12 activity causes dependency on the non-essential spliceosome components
AID  - 10.1101/2021.12.07.470703
DP  - 2021 Jan 01
TA  - bioRxiv
PG  - 2021.12.07.470703
4099  - http://biorxiv.org/content/early/2021/12/09/2021.12.07.470703.short
4100  - http://biorxiv.org/content/early/2021/12/09/2021.12.07.470703.full
AB  - Prostate cancer (PC) is the most common cancer in men and after development of the castration-resistant PC (CRPC), there are no curative treatment options. Inactivating mutations in cyclin-dependent kinase 12 (CDK12) define an aggressive sub-type of CRPC. We hypothesized that compromised CDK12 activity leads to significant rewiring of the CRPC cells, and that this rewiring results in actionable synthetic lethal interactions.Methods We used combinatorial lethal screening, ChIP-seq data, RNA-seq data, global alternative splicing analysis, and comprehensive mass spectrometry (MS) profiling to understand how the compromised CDK12 activity rewires the CRPC cells. In addition, we used DepMap-, PC- and CRPC-datasets as a strategy to identify factors that are selectively required by the CDK12-mutant cells.Results We show that inhibition of O-GlcNAc transferase (OGT) and CDK12 induces cancer cell-selective growth-defect. OGT catalyzes all nucleocytoplasmic O-GlcNAcylation, and we use unbiased MS-profiling to show that the short-term CDK12 inhibition induces hyper-O-GlcNAcylation of the spliceosome-machinery in PC and CRPC cells. Integration of DepMap- and a small scale-drug screen data reveled that depletion of CDK12 activity causes addiction to non-essential spliceosome components (CLK1/4 and SRPK1). CDK12-mutant tumors overexpress CLK1/4 and SRPK1. Finally, we show that the genomes of the CDK12-mutant tumors have lower DNA methylation, and that CDK12 inhibition induces the expression of the genes marked by DNA methylation.Conclusions Compromised CDK12 activity rewires DNA methylation, transcription and splicing, and this rewiring renders the affected cells addicted on the non-essential spliceosome components. We propose that inactivation of CDK12 is a biomarker for sensitivity against inhibitors of the non-essential spliceosome components just entering the clinical trials.Competing Interest StatementThe authors have declared no competing interest.