UNC0638

This assay utilizes SAHH to hydrolyze the methyltransfer product S-adenosylhomocysteine to homocysteine and adenosine in the presence of adenosine deaminase which converts adenosine to inosine. The homocysteine concentration is then determined through conjugation of its free sulfhydryl moiety to a thiol-sensitive fluorophore, ThioGlo. For IC50 determinations, assay mixtures are prepared in 25 mM Potassium Phosphate buffer pH 7.5, 1 mM EDTA, 2 mM MgCl₂, 0.01% Triton X 100 with 5 μM SAHH , 0.3 U/mL of adenosine deaminase, 25 μM SAM, and 15 μM ThioGlo. G9a, EHMT1, SETD7, SETD8, PRMT3 and SUV39H2 are assayed at 25 nM, 100 nM, 200 nM, 250 nM, 1 μM and 100 nM, respectively. UNC0638 is added at concentrations ranging from 4 nM to 16 μM. After 2 min incubation, reactions are initiated by addition of the histone peptides: 10 μM H3(1-25) for G9a, 20 μM H3(1-25) for EHMT1, 100 μM H3(1-25) for SETD7, 500 μM H4(1-24) for SETD8, 10 μM H4(1-24) for PRMT3 and 200 μM H3K9Me1 (1-15) for SUV39H2. The methylation reaction is followed by monitoring the increase in fluorescence using Biotek Synergy2 plate reader with 360/40 nm excitation filter and 528/20 nm emission filter for 20 min in 384 well-plate format. Activity values are corrected by subtracting background caused by the peptide or the protein. IC50 values are calculated using Sigmaplot. Standard deviations are calculated from two independent experiments.

MCF7, U2OS, H1299 cell lines

3 μM

65 h

Approximately 5×10⁵ cells were plated onto 75 cm² flasks. MCF7 and U2OS cells were grown in Minimal Essential Media (MEM) without phenol red supplemented with Earl's salts, 10% FBS, 1 mM Pyruvate, 2 mM Glutamine, and 1×non-essential amino acids. H1299 cells were grown in Dulbecco's Modified Eagle's Medium (DMEM) with phenol red supplemented with 10% FBS and 1×Anti-Anti. At the time of cell plating, media was supplemented with 3 μM UNC638A or the equivalent DMSO vehicle. The media with 3 μM UNC638A but without any cells was also used as a control. All flasks were incubated at 37℃/5% CO2. After 65 hours, media was collected from the cells and centrifuged to remove any cell debris. The media (10 to 15 mL) from each of study groups was mixed with HPLC grade chloroform (7 to 12 mL). After the mixture was gently shaken, it was allowed to sit until the organic layer and the aqueous layer separated. The organic layer was collected, dried over anhydrous Na₂SO₄, and concentrated in vacuo. The resulting residue was dissolved in 100 μL of methanol and the solution was analyzed using an Agilent 6110 LC/MS Series system with UV detector set to at 254 nm. Samples were injected (10 μL) onto a Phenomenex Kinetex 2.1 x 100 nm, 2.6 μM, C18 column at room temperature and eluted with 72% B (MeCN) with A being H2O + 0.1% formic acid. The flow rate was 0.3 mL/min. No degradation products of UNC0638 were observed for any of treatment groups.

Swiss albino mice

IV, 1 mg/kg; PO, 3 mg/kg; IP, 2.5 mg/kg

i.v./i.p./oral