Belinostat  (Synonyms: PXD101; PX105684)

For activity assays, the reaction is carried out in a total volume of 150 μL of buffer [60 mM Tris (pH 7.4) containing 30% glycerol] containing 2 μL of cell extract and, where used, 2 μL of Belinostat. The reaction is started by the addition of 2 μL of [³H]labeled substrate (acetylated histone H4 peptide corresponding to the 20 NH₂-terminal residues). Samples are incubated at 37°C for 45 min, and the reaction stopped by the addition of HCl and acetic acid (0.72 and 0.12 M final concentrations, respectively). Released [³H]acetate is extracted into 750 μL of ethyl acetate, and samples are centrifuged at 12,000× g for 5 min. The upper phase (600 μL) is transferred to 3 mL of scintillation fluid and counted^[1].

MCE has not independently confirmed the accuracy of these methods. They are for reference only.

The human ovarian cell line A2780 and Cisplatin (A2780/cp70) and Doxorubicin (2780AD) resistant derivatives are grown in RPMI 1640 supplemented with glutamine (2 mM) and FCS (10%). The human colon (HCT116 and HT29), melanoma (HS852), prostate (PC3), lung (CALU-3), and breast (MCF7) cell lines are grown in RPMI 1640 and the rest in DMEM supplemented as above. The human non-small cell lung cancer cell line WIL is grown in DMEM supplemented as above. Drug sensitivity is determined by a clonogenic assay. Briefly, cells are plated in 5 mL of medium at a density of 8×10⁴ cells/25 cm² flask and allowed to attach and grow for 48 h. Cells are exposed to Belinostat (five concentrations from 0.016 to 10 μM) for 24 h. The medium is removed, and 1 mL of trypsin/EDTA is added to each flask. Once the cells have detached, 1 mL of medium is added, the cells are resuspended, and those from the control untreated flask are counted. Cells are diluted and plated into 6-cm Petri dishes (three per flask) at a density of 500-2000 cells/dish depending on the cell line. Cells from the drug-treated flasks are diluted and plated as for the control flasks. Dishes are incubated for 10-15 days at 37°C. Cells are washed with PBS, fixed in methanol, and stained with crystal violet, and colonies that contained ≥50 cells counted. Sensitivity is expressed as the IC₅₀ (mean±SE of three experiments) defined as the concentration of drug required to reduce the number of colonies to 50% of that of the control untreated cells^[1].

MCE has not independently confirmed the accuracy of these methods. They are for reference only.

Mice^[1]
For the human tumor xenograft studies, monolayer cultures are harvested with trypsin/EDTA (0.25%/1 mM in PBS) and resuspended in PBS. About 10⁷ cells are injected s.c. into the right flank of athymic nude mice (CD1 nu/nu mice). After 10-15 days when the mean tumor diameter is ≥0.5 cm, animals are randomized into groups of six for experiments. Belinostat is dissolved in DMSO and then diluted in water to give a final concentration of DMSO of 10% and is administered i.p. at the times specified. This formulation gives sufficient solubility for doses of ≤ 40 mg/kg. Mice are weighed daily, and tumor volumes are estimated by caliper measurements assuming spherical geometry (volume=d³×π/6).

MCE has not independently confirmed the accuracy of these methods. They are for reference only.

• [1]. Plumb JA, et al. Pharmacodynamic response and inhibition of growth of human tumor xenografts by the novel histonedeacetylase inhibitor PXD101. Mol Cancer Ther. 2003 Aug;2(8):721-8.  [Content Brief]

  [2]. Qian X, et al. Activity of PXD101, a histone deacetylase inhibitor, in preclinical ovarian cancer studies. Mol Cancer Ther. 2006 Aug;5(8):2086-95.  [Content Brief]

  [3]. Chia S, et al. Phenotype-driven precision oncology as a guide for clinical decisions one patient at a time. Nat Commun. 2017 Sep 5;8(1):435.  [Content Brief]