NCIt definition : A selective inhibitor of the serine/threonine cyclin-dependent kinase 9 (CDK9), the
catalytic subunit of the RNA polymerase II (RNA Pol II) elongation factor positive
transcription elongation factor b (PTEF-b; PTEFb), with potential antineoplastic activity.
Upon administration, CDK9 inhibitor PRT2527 targets, binds to and blocks the phosphorylation
and kinase activity of CDK9, thereby preventing PTEFb-mediated activation of RNA Pol
II, leading to the inhibition of gene transcription of various anti-apoptotic proteins
and oncogenic transcription factors including MYC. This induces cell cycle arrest
and apoptosis and prevents tumor cell proliferation. CDK9 regulates elongation of
transcription through phosphorylation of RNA Pol II at serine 2 (p-Ser2-RNAPII), and
is an important cofactor for various oncogenic transcription factors. It is upregulated
in various tumor cell types and plays a key role in the regulation of Pol II-mediated
transcription of anti-apoptotic proteins. Tumor cells are dependent on anti-apoptotic
proteins for their survival.;