GSE60953
Compensatory induction of MYC expression by sustained CDK9 inhibition via a BRD4-dependent mechanism: Pol II occupancy profiling by ChIP-Seq in HeLa cell line in the presence or absence of CDK9 inhibition
CDK9 is the kinase subunit of P-TEFb that enables RNA polymerase (Pol) II to transit from promoter-proximal pausing to productive elongation. Although considerable interest exists in CDK9 as a therapeutic target, little progress has been made due to the lack of highly selective inhibitors. Here, we describe the development of i-CDK9 as such an inhibitor that potently suppresses CDK9 phosphorylation of substrates and causes genome-wide Pol II pausing. While most genes experience reduced expression, MYC and other primary response genes increase expression upon sustained i-CDK9 treatment. Essential for this increase, the bromodomain protein BRD4 captures P-TEFb from 7SK snRNP to deliver to target genes and also enhances CDK9’s activity and resistance to inhibition. Because the i-CDK9-induced MYC expression and binding to P-TEFb compensate for P-TEFb’s loss of activity, only the simultaneous inhibition of CDK9 and MYC can efficiently induce growth arrest and apoptosis of cancer cells, suggesting the potential of a combinatorial treatment strategy. Overall design: ChIP-seq of Pol II in HeLa cells before or after i-CDk9 treatment