Rabusertib (also known as IC-83; LY-2603618; LY 2603618; IC83) is a novel, potent and selective Chk1 (cell cycle checkpoint kinase 2) inhibitor with potential antitumor activity. It inhibits Chk1 with an IC50 of 7 nM in a cell-free assay and with potential anti-tumor activity. LY2603618 binds to and inhibits the activity of chk2, which may prevent the repair of DNA caused by DNA-damaging agents, thus potentiating the antitumor efficacies of various chemotherapeutic agents. Chk2, an ATP-dependent serine-threonine kinase, is a key component in the DNA replication-monitoring checkpoint system and is activated by double-stranded breaks (DSBs); activated chk2 is overexpressed by a variety of cancer cell types.
理化性质和储存条件
| Molecular Weight (MW) | 436.3 |
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| Formula | C18H22BrN5O3 |
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| CAS No. | 911222-45-2 |
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| Storage | -20℃ for 3 years in powder form |
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| -80℃ for 2 years in solvent |
| Solubility (In vitro) | DMSO: 13 mg/mL (29.8 mM) |
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| Water: <1 mg/mL |
| Ethanol: <1 mg/mL |
| Solubility (In vivo) | 2% DMSO+30% PEG400+0.5% Tween80+5% Propylene glycol: 30mg/mL |
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| Synonyms | IC-83; LY2603618; IC 83; LY 2603618; IC83; LY-2603618 |
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实验参考方法
| In Vitro | In vitro activity: Chk1 is an ATP-dependent serine-threonine kinase and a key component in the DNA replication-monitoring checkpoint system activated by double-stranded breaks (DSBs). Chk1 contributes to all currently defined cell cycle checkpoints, including G1/S, intra-S-phase, G2/M, and the mitotic spindle checkpoint. By inhibiting the activity of chk1, LY2603618 prevents the repair of DNA caused by DNA-damaging agents, thus potentiating the antitumor efficacies of various chemotherapeutic agents. However, preclinical data involving LY2603618 has not been published until now. Inhibition of Chk1 is predicted to enhance the effects of antimetabolites, such as gemcitabine. LY2603618 treatment impairs DNA synthesis, increases DNA damage (via mitotic defects), induces apoptosis, and has synergistic activity with pemetrexed, especially in p53 mutant tumor cells.
Kinase Assay: Rabusertib (LY2603618) is a highly effective inhibitor of multiple aspects of Chk1 biology. Rabusertib (LY2603618) is tested against a panel of 51 diverse protein kinases in vitro. With an IC50 of 7 nM for Chk1, Rabusertib (LY2603618) is approximately 100-fold more potent against Chk1 than against any of the other protein kinases evaluated (PDK1, IC50=893 nM, others>1000 nM). Rabusertib (LY2603618) effectively reduced Chk1 autophosphorylation with an EC50 of 430 nM. Inhibition of Chk1 by Rabusertib (LY2603618) also effectively abrogated the G2/M DNA damage checkpoint in cells treated with DNA damaging agents.
Cell Assay: LY2603618 inhibits Chk1 by competing with ATP molecules. In A549 and H1299 non-small cancer cell lines, lethal concentration of LY2603618 (10 μM) not only resulted in cell proliferation arrest (increase population of cell at G2/M phase from 13% to 38%) but also directly DNA damage, the latter of which was indicated by the increasing occurrence of H2AX phosphorylation. |
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| In Vivo | In vivo, experiment was carried out to determine the combining effect of LY2603618 with other chemotherapy. In mice xenograft model that inculated with Calu-6 lung cancer cell, combining administration of injected gemcitabine 150 mg/kg and orally uptake LY2603618 (200 mg/kg) resulted in increased DNA damage of tumour, as was demonstrated by a 2-fold increase in Chk1 s345 phosphorylation in comparison with mice treated with gemcitabine alone. |
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| Animal model | Mice |
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| Formulation & Dosage | Female Harlan athymic nude mice (26-28 g) are used for these studies. Tumor growth is initiated by subcutaneous injection of 1×106 Calu-6 cells in a 1:1 mixture of serum-free growth medium and Matrigel in the rear flank of each subject animal. When tumor volumes reach approximately 150 mm3 in size, the animals are randomized by tumor size and body weight, and placed into their respective treatment groups. Each animal receives 2 injections, one of either saline vehicle or 150 mg/kg Gemcitabine administered by intraperitoneal injection in a volume of 200 μL, and the other being the Captisol vehicle or LY2603618 administered orally in a volume of 200 μL. |
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| References | Clin Cancer Res. 2010 Jan 15;16(2):376-83; J Thorac Oncol. 2011 Nov;6(11 Suppl 4):S1757; Invest New Drugs. 2014 Apr;32(2):213-26. |
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