Systematic Kinase Inhibitor Profiling Identifies CDK9 as a Synthetic Lethal Target in NUT Midline Carcinoma

Cell Rep. 2017 Sep 19;20(12):2833-2845. doi: 10.1016/j.celrep.2017.08.082.

Abstract

Kinase inhibitors represent the backbone of targeted cancer therapy, yet only a limited number of oncogenic drivers are directly druggable. By interrogating the activity of 1,505 kinase inhibitors, we found that BRD4-NUT-rearranged NUT midline carcinoma (NMC) cells are specifically killed by CDK9 inhibition (CDK9i) and depend on CDK9 and Cyclin-T1 expression. We show that CDK9i leads to robust induction of apoptosis and of markers of DNA damage response in NMC cells. While both CDK9i and bromodomain inhibition over time result in reduced Myc protein expression, only bromodomain inhibition induces cell differentiation and a p21-induced cell-cycle arrest in these cells. Finally, RNA-seq and ChIP-based analyses reveal a BRD4-NUT-specific CDK9i-induced perturbation of transcriptional elongation. Thus, our data provide a mechanistic basis for the genotype-dependent vulnerability of NMC cells to CDK9i that may be of relevance for the development of targeted therapies for NMC patients.

Keywords: CDK9 inhibitor; NUT midline carcinoma; high-throughput screen; transcriptional elongation.

MeSH terms

  • Cell Cycle Proteins
  • Cell Line, Tumor
  • Cyclin T / metabolism
  • Cyclin-Dependent Kinase 9 / antagonists & inhibitors
  • Cyclin-Dependent Kinase 9 / metabolism
  • HEK293 Cells
  • High-Throughput Screening Assays
  • Humans
  • Molecular Targeted Therapy*
  • Neoplasms / enzymology*
  • Neoplasms / genetics
  • Neoplasms / pathology*
  • Nuclear Proteins / antagonists & inhibitors
  • Nuclear Proteins / metabolism
  • Protein Kinase Inhibitors / chemistry
  • Protein Kinase Inhibitors / pharmacology*
  • RNA Polymerase II / metabolism
  • Transcription Elongation, Genetic / drug effects
  • Transcription Factors / antagonists & inhibitors
  • Transcription Factors / metabolism
  • Transcription, Genetic / drug effects

Substances

  • BRD4 protein, human
  • Cell Cycle Proteins
  • Cyclin T
  • Nuclear Proteins
  • Protein Kinase Inhibitors
  • Transcription Factors
  • CDK9 protein, human
  • Cyclin-Dependent Kinase 9
  • RNA Polymerase II