CDK12 controls transcription at damaged genes and prevents MYC-induced transcription-replication conflicts.

The identification of genes involved in replicative stress is key to understanding cancer evolution and to identify therapeutic targets. Here, we show that CDK12 prevents transcription-replication conflicts (TRCs) and the activation of cytotoxic replicative stress upon deregulation of the MYC oncogene. CDK12 was recruited at damaged genes by PARP-dependent DDR-signaling and elongation-competent RNAPII, to repress transcription. Either loss or chemical inhibition of CDK12 led to DDR-resistant transcription of damaged genes. Loss of CDK12 exacerbated TRCs in MYC-overexpressing cells and led to the accumulation of double-strand DNA breaks, occurring between co-directional early-replicating regions and transcribed genes. Overall, our data demonstrate that CDK12 protects genome integrity by repressing transcription of damaged genes, which is required for proper resolution of DSBs at oncogene-induced TRCs. This provides a rationale that explains both how CDK12 deficiency can promote tandem duplications of early-replicated regions during tumor evolution, and how CDK12 targeting can exacerbate replicative-stress in tumors. CDK12 is a therapeutic target and cancer gene required for genome integrity. Here, the Authors show that loss or inhibition of CDK12 leads to persistent transcription of damaged genes, and triggers transcription replication conflicts leading to selective cell death in Myc- driven tumors. [ABSTRACT FROM AUTHOR]