Palbociclib (PD 0332991) is a CDK inhibitor that inhibits CDK4 and CDK6 (IC50=11/16 nM) and is orally active. Palbociclib has anti-tumorigenic activity and has investigational potential for use in ER-positive and HER2-negative breast cancer.

CDK4:11 nM, CDK6:16 nM

方法：恶性横纹肌样瘤细胞 G401、MP-MRT-AN (AN)、KP-MRT-RY (RY)、KP-MRT-NS (NS) 和 KP-MRT-YM (YM) 用 Palbociclib (0-1 mM) 处理 24 h，使用 WST 方法检测细胞活力。
结果：Palbociclib 以浓度依赖性的方式有效抑制 AN、RY、G401 和 NS 细胞系，IC50 分别为 0.01 μM、0.01 μM，0.06 μM 和 0.6 μM。相反，YM 细胞系对 Palbociclib 具有抗性，IC50>10 μM。[1]
方法：人乳腺癌细胞 MDA-MB-453 用 Palbociclib (0.02-10 μmol/L) 处理 24 h，使用 Flow Cytometry 方法检测细胞周期情况。
结果：Palbociclib 导致 G1 期阻滞。[2]

方法：为检测体内抗肿瘤活性，将 Palbociclib (12.5-150 mg/kg，sodium lactate buffer (50 mmol/L, pH 4.0)) 口服给药给携带肿瘤 Colo-205 或 MDA-MB-435 的免疫缺陷小鼠，每天一次，持续十四天。
结果：Palbociclib 对多种人类肿瘤异种移植物模型显示出显著的抗肿瘤功效。对 Colo-205 肿瘤，PD 0332991 给药 14 天，可产生快速的肿瘤消退。[2]
方法：为检测体内抗肿瘤活性，将 Palbociclib (150 mg/kg，sodium lactate buffer (50 mM, pH = 4.0)) 灌胃给药给携带食道鳞状细胞癌 (ESCC) 肿瘤 EC109 或 KYSE150 的 nu/nu BALB/c 小鼠，每天一次，持续两周。
结果：Palbociclib 有效抑制 ESCC 肿瘤生长和肺转移。[3]

CDK assays are performed in 96-well filter plates. All CDK-cyclin kinase complexes are expressed in insect cells through baculovirus infection and purified. The substrate for the assays is a fragment (amino acids 792-928) of pRb fused to GST (GST·RB-Cterm). The total volume in each well is 0.1 mL containing a final concentration of 20 mM Tris-HCl, pH 7.4, 50 mM NaCl, 1 mM dithiothreitol, 10 mM MgCl2, 25 μM ATP (for CDK4-cyclin D1, CDK6-cyclin D2, and CDK6-cyclin D3) or 12 μM ATP (for CDK2-cyclin E, CDK2-cyclin A, and CDC2-cyclin B) containing 0.25 μCi of [γ-32P]ATP, 20 ng of enzyme, 1 μg of GST·RB-Cterm, and Palbociclib (0.001-0.1 μM). All components except the [γ-32P]ATP are added to the wells, and the plate is placed on a plate mixer for 2 min. The reaction is started by adding the [γ-32P]ATP and the plate is incubated at 25°C for 15 min. The reaction is terminated by addition of 0.1 mL of 20% trichloroacetic acid and the plate is kept at 4°C for at least 1 hour to allow the substrate to precipitate. The wells are then washed 5 times with 0.2 mL of 10% trichloroacetic acid and radioactive incorporation is determined with a β plate counter.

Palbociclib (PD) is prepared in DMSO and stored (?80°C), and then diluted with appropriate media before use[1]. MRT cell lines, G401, MP-MRT-AN (AN), KP-MRT-RY (RY), KP-MRT-NS (NS), and KP-MRT-YM (YM) cell lines are seeded in normal growth medium into 96-well cell plates. After 24 h, the culture medium is replaced with culture medium containing Palbociclib (0.05 or 1 μM) or DMSO. Cells are cultured and treated in triplicate. Cell proliferation is determined 8 days after the treatment by WST-8 assay using a Cell Counting Kit-8.