| References: |
Palbociclib isethionate(PD-0332991 isethionate) is a highly specific inhibitor of Cdk4 (IC50=11 nM) and Cdk6 (IC50=16 nM), having no activity against a panel of 36 additional protein kinases.
in vitro: ATP competitive inhibitor of Cdk4. PD 0332991 inhibits MDA-MB-435 breast carcinoma cells with IC50 of 66 nM, which is due to reduced Rb phosphorylation at Ser780. PD 0332991 inhibits thymidine incorporation into the DNA of Rb-positive human breast, colon, and lung carcinomas as well as human leukemias, with IC50 values ranging from 0.04-0.17 μM. PD 0332991 shows no activity in Rb-negative cells. PD 0332991 causes an accumulation of cells in G1 in MDA-MB-453 breast and Colo-205 carcinoma cells . PD 0332991 inhibits luminal ER-positive as well as HER2-amplified breast cancer cell lines including MDA-MB-175, ZR-75-30, CAMA-1, MDA-MB-134, HCC-202 and UACC-893. PD 0332991 enhances the activity of tamoxifen and trastuzumab in these cell lines. PD 0332991 enhances the sensitivity of tamoxifen in the MCF7 tamoxifen-resistant cells. PD 0332991 could suppress malignant rhabdoid tumor (MRT) cell lines including MP-MRT-AN, KP-MRT-RY, G401, KP-MRT-NS and the sensitivity of the MRT cell lines to PD 0332991 is inversely correlated with expression of p16.
in vivo: PD 0332991 indicates complete tumor stasis in a MDA-MB-435 xenograft at 150 mg/kg. PD 0332991 also shows broad-spectrum antitumor activity in multiple human tumor xenografts by eliminating phospho-Rb and the proliferative marker Ki-67 from tumor tissue and down-regulation of genes under the transcriptional control of E2F. |
