PAC-1 (Procaspase activating compound 1) has been used in trials studying the treatment of Lymphoma, Melanoma, Solid Tumors, Breast Cancer, and Thoracic Cancers, among others.

Procaspase-3:0.22 μM(EC50)

PAC-1由于激活procaspase-3和随后诱导凋亡发挥体内抗肿瘤效果,与体外活性一致.用5 mg的稳定释放低剂量PAC-1处理小鼠,明显抑制ACHN肾移植瘤生长.用50或100 mg/kg PAC-1口服处理,明显剂量依赖性阻碍NCI-H226肺癌移植瘤生长,且明显阻止癌细胞浸润肺组织.

PAC-1能够以延迟的方式诱导Bax/Bak双敲除细胞和Bcl-2和Bcl-xL过表达细胞中的细胞死亡,具有与野生型对应物相同的功效。PAC-1按caspase-3 非依赖性方式诱导细胞色素c释放,随后触发下游caspase-3激活和细胞死亡。PAC-1不能诱导Apaf-1敲除细胞中的细胞死亡和半胱天冬酶-3激活,这表明凋亡体形成对于通过PAC-1介导的细胞死亡的胱天蛋白酶-3激活是必需的。PAC-1诱导原发性癌细胞凋亡,IC50值为3 nM至1.41 μM,比邻近的非癌细胞更有效,IC50为5.02 μM至9.98 μM,这也与procaspase-3的浓度直接相关。PAC-1激活procaspase-3,产生caspase-3,EC50为 0.22 μM,且激活procaspase-7,EC50为 4.5 μM。癌细胞系中增高的caspase 3水平使 PAC-1 选择性诱导凋亡,按与procaspase-3 浓度成比例的方式,NCI-H226细胞的IC50为0.35 μM,UACC-62细胞的IC50为约3.5 μM。PAC-1通过螯合锌离子来激活胱天蛋白酶-3,从而减轻锌介导的抑制作用,并允许胱天蛋白酶原-3自身激活为胱天蛋白酶-3。

In vitro procaspase-3 activation: Procaspase-3 is expressed and purified in Escherichia coli. Various concentrations of PAC-1 are added to 90 μL of a 50 ng/mL of procaspase-3 in caspase assay buffer in a 96-well plate, The plate is incubated for 12 hours at 37 °C. A 10 μL volume of a 2 mM solution of caspase-3 peptidic substrate acetyl Asp-Glu-Val-Asp-p-nitroanilide (Ac-DEVD-pNa) in caspase assay buffer is then added to each well. The plate is read every 2 minutes at 405 nm for 2 hours in a Spectra Max Plus 384 well plate reader. The slope of the linear portion for each well is determined, and the relative increase in activation from untreated control wells is calculated.

Cells are exposed to various concentrations of PAC-1 for 72 hours. Cell death is quantified by the addition of MTS/PMS CellTiter 96 Cell Proliferation Assay reagent. The plates are incubated at 37 °C for approximately 1 hour (until the colored product formed), and the absorbance is measured at 490 n(Only for Reference)