Procaine (Vitamin H3) is a local anesthetic of the ester type that has a slow onset and a short duration of action. It is mainly used for infiltration anesthesia, peripheral nerve block, and spinal block.

Procaine显著降低了HLE、HuH7和HuH6细胞的活性。Procaine在对HLE细胞实验时观察到S/G2/M周期转换受阻、形态学变化如空泡化，但凋亡率并未增加。Procaine处理后因DNA过度甲基化而转录抑制的基因被去甲基化并重新激活。Procaine对人类肝癌细胞具有生长抑制和去甲基化作用[2]。

Procaine 在体内对异种移植瘤具有生长抑制和脱甲基作用[2]。

Biochemical Assays: Compound potency is also assessed through incorporation of 3H-SAM into a biotinylated H3 peptide. Specifically, PRC2 containing either EZH1 (160 pM), wt EZH2 (40 pM), or Y641N mutant EZH2 (80 pM, both EZH2 prepared in-house) is pre-incubated with 3H-SAM (0.9 μM), 2 μM H3K27me3 activating peptide (H2N-RKQLATKAAR(Kme3)SAPATGGVKKP-amide) and compounds (as 10 point duplicate dose response titrations) for 120 min in a buffer consisting of 50 mM Tris (pH 8.5), 1 mM DTT, 0.07 mM Brij-35, 0.1% BSA, and 0.8% DMSO in a total volume of 12.5 μl in a black 384 well plate. Reaction is initiated with biotinylated H3 substrate peptides (H3K27me1 for wt EZH2, H3K27me2 for Y641N mutant EZH2; H2N-RKQLATKAAR(Kmen)SAPATGGVKKP-NTPEGBiot) as a 2 μM stock in 12.5 μL and allowed to react at room temperature for 5 h. Quenching is accomplished by addition of 20 μl of STOP solution (50 mM Tris (pH 8.5), 200 mM EDTA, 2 mM SAH). 35 μL of the quenched solution is transferred to Streptavidin Flashplates, incubated overnight, washed, and read in a TopCount Reader. For titrations all compound dilutions are in DMSO, final DMSO concentrations are 0.8% (v/v), and turnover is kept to less than < 5%. IC50s are calculated using non-linear least square four parameter fits (GraphPad 6.0).

For apoptosis analysis, the TUNEL assay is performed on HLE cells treated with no drug(control), or 1 μM of DAC(5-aza-2'-deoxycytidine), or 1 mM of PCA(procaine), or 1 mM of PCAA(procainamide) for 96 h. The proportion of TUNEL-positive cells was calculated by counting at least 500 cells randomly. All assays were carried out in triplicate. (Only for Reference)