Development of a Selective CDK7 Covalent Inhibitor Reveals Predominant Cell-Cycle Phenotype

Area of Science:

• Molecular Biology
• Cell Biology
• Pharmacology

Background:

• Cyclin-dependent kinase 7 (CDK7) plays a role in cell cycle and transcription.
• Previous CDK7 inhibitors like THZ1 had off-target effects on CDK12/13, obscuring CDK7's specific role.
• Understanding CDK7's precise function is crucial for cancer therapy.

Purpose of the Study:

• To discover and characterize a highly selective covalent CDK7 inhibitor.
• To elucidate the specific role of CDK7 in gene expression and cell cycle regulation.
• To investigate the potential of selective CDK7 inhibition in cancer treatment.

Main Methods:

• Discovery and synthesis of a selective covalent CDK7 inhibitor, YKL-5-124.
• Utilizing a CDK7 mutant to confirm on-target specificity of YKL-5-124.
• Assessing effects on cell cycle (G1/S transition) and gene expression (E2F-driven).
• Comparing YKL-5-124 effects with THZ1 and a selective CDK12/13 inhibitor (THZ531).

Main Results:

• YKL-5-124 selectively inhibits CDK7, causing G1/S cell cycle arrest and suppressing E2F-driven gene expression.
• On-target specificity was confirmed using a resistant CDK7 mutant.
• YKL-5-124 did not affect RNA polymerase II C-terminal domain phosphorylation, unlike THZ1.
• Combined inhibition of CDK7 and CDK12/13 revealed potential transcriptional redundancies.

Conclusions:

• Selective CDK7 inhibition by YKL-5-124 effectively targets cell cycle and E2F-driven transcription.
• CDK7/12/13 polypharmacology is important for the anti-cancer activity of non-selective inhibitors like THZ1.
• Selective CDK7 inhibition may offer a therapeutic strategy for cancers with E2F misregulation.