NU6027 is a potent ATR/CDK inhibitor, inhibits CDK1/2, ATR and DNA-PK with Ki of 2.5 μM/1.3 μM, 0.4 μM and 2.2 μM, enter cells more readily than the 6-aminopurine-based inhibitors.

DNA-PK:2.2 μM(Ki), CDK2:1.3 μM(Ki), CDK1:2.5 μM(Ki), ATR:0.4 μM(Ki)

NU6027浸渍单体CDK2晶体，并将结构精细化至1.85埃分辨率。NU6027 (100 μM) 对人类肿瘤细胞的生长抑制作用表现出平均GI50为10 μM。NU6027能减少MCF7细胞S期的细胞数量，但对G1期或G2/M期无影响。[1] NU6027是一种强效的细胞内ATR活性抑制剂，其IC50在MCF7细胞中为6.7 μM，在GM847KD细胞中为2.8 μM，且以ATR依赖的方式增强了羟基脲和顺铂的细胞毒性。NU6027 (10 μM) 抑制CDK2介导的pRbT821 42%和pCHK1S345 70%。NU6027显著增强了对顺铂(1.4倍于4 μM和8.7倍于10 μM)、多柔比星(1.3倍于4 μM和2.5倍于10 μM)、喜树碱(1.4倍于4 μM和2倍于10 μM)和羟基脲(1.8倍于4 μM)在MCF7细胞中的敏感性。NU6027还以浓度依赖性的方式增强了2 gy IR的敏感性，以及喜树碱和替莫唑胺（一种DNA甲基化剂）在其LC50以上和以下浓度的细胞毒性。NU6027 (10 μM) 减弱DNA损伤后的G2/M阻滞，抑制RAD51焦点形成，并增加对DNA损伤的主要类别的抗癌细胞毒疗法的细胞毒性，但不影响抗有丝分裂剂，紫杉醇在MCF7细胞中的作用。NU6027 (4 μM) 在DNA单链断裂修复受损时表现出合成致死性，无论是通过poly(ADP-ribose) polymerase (PARP)抑制还是XRCC1缺陷在MCF7细胞中。[3] NU6027 (4 μM) 在48小时处理后使EM-C11细胞早期凋亡的比例增加到7.5%，与未处理细胞的1.73%相比。与高效细胞相比，NU6027 (10 μM) 处理降低了XRCC1缺陷的OVCAR-4细胞的生存率。与XRCC1高效细胞相比，NU6027增强了顺铂在XRCC1缺陷的OVCAR-3细胞中的细胞毒性。NU6027增强了顺铂在XRCC1缺陷的OVCAR-3细胞中诱导的DSB积累。[4]

Enzyme Inhibition Studies: Inhibition of cyclin B1/CDK1 is assayed using enzyme prepared from starfish oocytes. Inhibition of cyclinA3/CDK2 is determined using a similar assay and an assay buffer comprised of 50 mM Tris-HCl pH 7.5 containing 5 mM MgCl2. The final ATP concentration in both CDK assays is 12.5 μM, and the IC50 concentration for NU6027 is the concentration required to inhibit enzyme activity by 50% under the assay conditions used. To determine the Km for ATP for cyclin B1/CDK1 and cyclin A3/CDK2, and Ki values for NU6027, assays are performed in the absence of NU6027 and at two fixed NU6027 concentrations (5 μM and 10 μM), with ATP concentrations ranging from 6.25 μM to 800 μM. Data are fitted to the Michaelis?Menten equation using unweighted nonlinear least squares regression.

The growth inhibitory activity of the NU6027 is evaluated in the NCl in vitro cell line panel using the standard 48 hours exposure assay and NU6027 concentrations ranging from 10-9 to 10-4 M. Relationships between the profile of cell growth inhibition produced by NU6027 and that of standard anticancer agents, and the established CDK inhibitors olomoucine and flavopiridol, is investigated using the COMPARE algorithm. (Only for Reference)