SCH900776 (MK-8776) is an agent targeting cell cycle checkpoint kinase 1 (Chk1) with potential radiosensitization and chemosensitization activities.

Chk1:3 nM, CDK2:0.16 μM

在吉西他滨后30分钟给药,4 mg/kg SCH 900776足以诱导γ-H2AX生物标志物,而8 mg/kg SCH 900776增强肿瘤药效动力学和退化响应.递增剂量16 mg/kg和32 mg/kg的SCH 900776诱导肿瘤响应持续改进.重要的是,在BALB/c小鼠体内,SCH 900776剂量与强的生物标志物活化相关,而提高的肿瘤响应与吉西他滨对血液学指标增强的毒性无关.

羟基脲暴露24小时后,SCH 900776诱导DNA复制能力的剂量依赖性丧失。SCH 900776增强γ-H2AX对羟基脲,5-氟尿嘧啶和阿糖孢苷的响应。SCH 900776与抗代谢物结合,在2小时内诱导γ-H2AX的累积,表明复制叉瓦解和并且双链DNA断裂。此外,SCH 900776以剂量依赖的方式抑制Chk1 pS296自磷酸化的积累。SCH 900776是Chk2和CDK2的低效抑制剂,IC50分别为1.5 μM和0.16 μM。SCH 900776对细胞色素P450人肝微粒体亚型1A2,2C9,2C19,2D6和3A4没有明显的抑制作用。

The Millipore Kinase Profiler service is used to generate general selectivity data for SCH 900776 against a broad range of serine/threonine and tyrosine kinases. Assays are typically run at two concentrations of SCH 900776 (0.5 and 5 μM), at a fixed (10 μM) concentration of ATP. Data are provided as percent activity remaining, relative to uninhibited controls.

For cell growth assays, cells are seeded at low density (500-1000 cells) in 96-well plates and then incubated with drug for 24 h (8 wells per concentration). Following treatment, cells are washed and grown in fresh media for 5-7 days at 37°C. Prior to attaining confluence, cells are washed, lysed, and stained with Hoechst 33258. Fluorescence is read on a microplate spectrofluorometer. Results are expressed as mean and standard error for the concentration of drug that inhibited growth by 50%.