An inhibitor of Cdk2 and Cdk9
Fadraciclib is an inhibitor of cyclin-dependent kinase 2 (Cdk2) and Cdk9 (IC50s = 4.5 and 20.5 nM, respectively).1 It is selective for Cdk2 and Cdk9 over Cdk1, -4, and -7 (IC50s = 278, 193, and 232 nM, respectively). Fadraciclib inhibits the proliferation of COLO 205 cells (IC50 = 0.31 ?M), as well as inhibits proliferation in a panel of five breast cancer cell lines (IC50s = <0.4 ?M for all). It decreases phosphorylation of the RNA polymerase II C-terminal domain and RB, Cdk9 and Cdk2 targets, respectively, and induces apoptosis in COLO 205 cells. Fadraciclib (40 and 55 mg/kg) reduces tumor volume in an EoL-1 eosinophilic leukemia mouse xenograft model. It also inhibits tumor growth in an HL-60 mouse xenograft model when administered at a dose of 70 mg/kg.
1.Frame, S., Saladino, C., MacKay, C., et al.Fadraciclib (CYC065), a novel CDK inhibitor, targets key pro-survival and oncogenic pathways in cancerPLoS One15(7)e0234103(2020)
Cell experiment: | The effect of CYC065 on the viability and IC50 of USC-ARK-1, USC-ARK-2, USC-ARK-7, USC-ARK-4 and USC-ARK-6 USC primary cell lines is determined in flow-cytometry assay. Briefly, tumour cells are plated in six-well plates and treated with a titration of CYC065 concentrations (i.e., ranging from 100 to 500?nM). After 72?h, cells are harvested, washed and stained with propidium iodide (PI; 5?μg/mL) for flow cytometric counts. The percentage of viable cells is then normalised considering the vehicle-treated cells as 100% viable. Half-maximal inhibitory concentration values are determined using GraphPad Prism5 version 6. For drug combination studies, USC-ARK-1 and USC-ARK-2 cell lines are incubated with the combination of Taselisib and CYC065 at multiple paired concentrations including the IC50, the IC50/2 and the IC50*2 of each cell line to the corresponding drug (i.e., 10?nM of Taselisib and 198?nM of CYC065 for USC-ARK-1 and 50?nM of Taselisib and 62.5?nM of CYC065 for USC-ARK-2). Synergism is assessed by the combination index (CI). CI values <1 define a synergistic activity of the combination treatment. The CI values are calculated using the CompuSyn software[1]. |
Animal experiment: | Mice[1] The in vivo efficacy of CYC065 used as a single agent is evaluated on xenograft mouse models derived from the CCNE1-amplified USC-ARK-2 USC cell line. Xenografts derived from the CCNE1-amplified, PIK3CA-mutated USC-ARK-1 cell line are used for evaluating the in vivo combination of CYC065 and Taselisib. Briefly, 5-7-week-old SCID mice are injected into the subcutaneous region with USC cells. A minimum of five animals per group are used. Treatments are administrated by oral gavage starting 1 week after tumor implantation when the size of the tumor is 0.125-0.150?cm3. Uterine serous carcinoma-ARK-2-derived xenografts are divided into two groups: one group of animal receive the vehicle, whereas the experimental group receive CYC065 (22.5?mg/kg daily for 3 weeks). Uterine serous carcinoma-ARK-1-derived xenografts are instead divided into four groups: one group receive the vehicle (0.5% methylcellulose-0.2% Tween-80), one group receive CYC065 (22.5?mg/kg daily for 3 weeks), one group receive Taselisib (10 mg/kg daily, 5 days per week per 3 weeks) and the last group receive the combination of CYC065 and Taselisib. The size of the tumor at the initiation of treatment is 0.125-0.150?cm3. Mouse weight and tumor size is recorded two times a week for the entire experimental period. Tumor volume is calculated. |
参考文献: [1]. Cocco E, et al. Dual CCNE1/PIK3CA targeting is synergistic in CCNE1-amplified/PIK3CA-mutated uterine serous carcinomas in vitro and in vivo. Br J Cancer. 2016 Jul 26;115(3):303-11. | |
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