KRIBB11 is an inhibitor of Heat shock factor (HSF) inhibitor.

HSF1:1.2 μM

KRIBB11以浓度依赖的方式抑制HSF1活性。它降调HSP70和HSP27的表达。KRIBB11能够抑制癌症细胞增殖，使细胞周期在G2/M阶段停滞并诱导凋亡。但它不抑制热激诱导的HSF1向hsp70启动子的招募或HSF1 Ser-230的磷酸化。KRIBB11抑制热激诱导的pTEFb向hsp70启动子的招募以及p-TEFb依赖的polⅡ CTD Ser-2的磷酸化[1]。

在小鼠异种移植模型中，与未经处理的对照小鼠相比，KRIBB11治疗可使肿瘤体积减少47%。此外，接受KRIBB11处理的小鼠肿瘤中HSP70蛋白水平显著降低，这支持了KRIBB11通过抑制HSF1发挥其体内抗肿瘤活性的观点[1]。

HCT-116 cells are washed with PBS and then homogenized with a 27-gauge syringe in binding buffer (10 mm Tris-HCl (pH 7.4), 50 mm KCl, 5 mm MgCl2, 1 mm EDTA, and 0.1 mm Na3VO4). The cell lysate is centrifuged at 13,000 rpm for 30 min at 4°C, and the supernatant is collected. The HCT-116 cell lysate supernatant is precleared by incubating with Dynabeads M-280 streptavidin for 30 min at 4°C and captured by magnet separation. The cleared supernatants are incubated with biotinyl-KRIBB11 compound. After overnight incubation at 4°C, proteins associated with the biotinyl-KRIBB11 compound are precipitated with Dynabeads M-280 streptavidin. Precipitated samples are separated by a magnet. Samples are washed with 1 mL of ishing buffer containing 50 mm HEPES (pH 7.5), 50 mm NaCl, 1 mm EDTA, 1 mm EGTA, 0.1% Tween 20, 10% (v/v) glycerol, 1 mm NaF, 0.1 mm Na3VO4, and protease inhibitor mixture tablets (1 tablet/10 mL). Samples are boiled in SDS-PAGE sample buffer, separated by 10% polyacrylamide gel, and immunoblotted with antibodies against HSF1, HSF2, HSP90, or CDK9.

HCT-116 cells are treated with KRIBB11 at various concentrations for 48 h. Cells are then harvested by trypsinization, fixed with 70% chilled ethanol, and preserved at ?20 °C before FACS analysis. Fixed cells are washed twice with phosphate-buffered saline (PBS) solution before being suspended in 500 μl of PBS and treated with 100 mg/ml RNase A at 37 °C for 30 min. Propidium iodide is then added to a final concentration of 50 mg/ml for DNA staining, and 20,000 fixed cells are analyzed on a FACSCalibur system. Cell cycle distribution is analyzed using the ModFit program.(Only for Reference)