PD 0332991 is an orally active, selective inhibitor of the cyclin D kinases Cdk4 (IC50 = 11 nM) and Cdk6 (IC50= 16 nM) with no activity against a panel of 36 additional protein kinases. It has been reported to have antiproliferative activity against retinoblastoma-positive tumor cells, blocking retinoblastoma phosphorylation and inducing G1 arrest at nanomolar concentrations. PD 0332991 can inhibit the growth of certain ER-positive or HER2-amplified breast cancer cells (IC50s as low as 4 nM) and demonstrates synergy with tamoxifen and trastuzumab, respectively. PD 0332991 inhibition of Cdk4 activity has been used to demonstrate a role for insulin-activated cyclinD1-Cdk4 signaling in the control of glucose metabolism that is independent of cell cycle progression.
A cell-permeable, orally available and brain permeant, non-toxic pyridopyrimidinone compound that acts as a potent, selective, reversible, ATP competitive inhibitor of Cdk4 and Cdk6 (IC
50 = 11, 9, and 15 nM for Cdk4/D1, Cdk4/D3 and Cdk6/D2, respectively). Hence, it reduces retinoblastoma protein phosphorylation at Ser780/Ser795 (IC
50 = 66 nM in MDA-435 cells) and arrests cell cycle at G1 phase. Acts as a cytostatic agent, but does induce apoptotic cell death when used alone. However, it potentiates the cytotoxicity of dexamethasone (
>Cat. No. 265005), bortezomib (
>Cat. No. 504314), and tamoxifen (
Cat. No. 579000) in estrogen receptor (ER)-positive cell lines. Exhibits only a trivial inhibitory activity towards Cdk2/E2, Cdk2/A, Cdk1/B and Cdk5/p25 in a 36-kinase panel (IC
50 >10 μM). Improves endoderm differentiation of late G1-human embryonic stem cells expressing Smad2 or Smad3 (~ 750 nM) and further enhances endoderm differentiation into hepatic and pancreatic progenitor cells. Shown to regress the growth of human breast tumor xenografts in murine models (~150 mg/kg, p.o., daily).