Cyclin-dependent kinase 12 (CDK12) (CDK12)

Cyclin-dependent kinase 12 (CDK12) is a transcription-associated serine/threonine kinase that forms a functional heterodimeric complex with Cyclin K to regulate gene expression [1, 4, 16]. It primarily functions by phosphorylating the Serine 2 residue of the RNA polymerase II C-terminal domain, which is essential for productive transcription elongation, particularly for long, complex genes involved in the DNA damage response (DDR) and homologous recombination (HR) [2, 3, 14]. In oncology, CDK12 is recognized as both a tumor suppressor and an oncogene depending on the cellular context; loss-of-function mutations lead to a distinct genomic instability phenotype characterized by focal tandem duplications, while its amplification (often co-occurring with HER2) promotes tumor cell survival and resistance [1, 3, 7, 18]. Therapeutic targeting of CDK12 involves the use of small-molecule inhibitors, PROTACs, and molecular glues to induce synthetic lethality in DDR-deficient tumors or to suppress oncogenic transcriptional programs [4, 9, 11, 12]. Clinical development of CDK12-targeted agents faces challenges such as high homology with CDK13 and potential systemic toxicities related to its essential role in normal tissue homeostasis and embryonic development [2, 6, 10, 17].

Other names

CRKRS (Cdc2-related kinase with an arginine/serine-rich domain)CRK7 (Cell division cycle 2-related protein kinase 7)CRKRCDC2L7hCDK12

Kinase inhibition (ATP-competitive and covalent), targeted protein degradation (PROTACs), and molecular glue-induced degradation of the Cyclin K subunit [4, 9, 11].