Chk1 (Checkpoint kinase 1), an important serine/threonine kinase, is responding to DNA damage and stall DNA replication. Chk1 plays a key role in maintaining the replication fork viability during exposure to DNA antimetabolites. Inhibition of Chk1 will lead to accumulation of double-strand DNA breaks and cell death in human tumor cell lines exposure to antimetabolite. LY2603618 (Rabusertib) is a selective inhibitor of Chk1 with IC50 value of 7nM (measured by protein kinase assays). Treatment with 14-3300nM LY2603618 for 2h can dose-dependently decrease the level of phosphorylated Chk1 serine 296, an autophosphorylation reflecting Chk1 catalytic activity, in HeLa cells incubated with 100nM doxorubicin for 24h. Similar result can also be obtained in Calu6 Cells treated with 60nM gemcitabine. After treatment with LY2603618 1250 or 5000nM for 24h, increased level of p-H2A.X-S139 and p-H3-S10, the markers of DNA damage and mitotic, can be observed in HeLa cells. Meanwhile, a clear decrease in the G1 population and an increase in late S-phase cells, as well as cell arrest in an aberrant prometaphase state by LY2603618 can be observed. These indicated that inhibition of Chk1 by LY2603618 can abrogate the S-phase checkpoint. An increase in staining of the mitotic marker p-H3-Ser10 can be observed in HeLa cells treated for 24h with 100nM doxorubicin to cause a G2 arrest, then for 7h with serially diluted LY2603618. This indicated that LY2603618 can inactivate the G2/M DNA damage checkpoint[1]. Combining 200mg/kg of LY2603618 with 160mg/kg of gemcitabine increased the tumor growth delay compared with gemcitabine alone in Calu-6 and HT-29 xenograft tumor models[2]. Up to now, phase 2 studies of LY2603618 treatment for non small cell lung cancer and pancreatic neoplasms have been completed (see https://www.clinicaltrials.gov/).
作用机制
LY2603618 bound in the ATP binding site of Chk1.
Rabusertib 细胞实验
Cell Line
Concentration
Treated Time
Description
References
ID8agg cells
2.5 μM
72 h
Rabusertib induced DNA damage and increased γH2AX expression
Int J Mol Sci. 2022 May 4;23(9):5129.
ID8agg cells
2.5 μM
96 h
To investigate the effects of Rabusertib on PDL1 expression in tumor cells and the combination effects with Cefepime. The results showed that Cefepime significantly reduced PDL1 overexpression induced by Rabusertib and enhanced its cytotoxic effects
Int J Mol Sci. 2022 May 4;23(9):5129.
ID8agg cells
80 μM
96 h
Cefepime significantly improved the efficacy of the Chk1 inhibitor rabusertib
Int J Mol Sci. 2022 May 4;23(9):5129.
PDAC cell lines
125 nM to 1 µM
24 h
To determine the inhibitory effect of Rabusertib on PDAC cells, results showed that Rabusertib significantly reduced cell survival.
Mol Cell Proteomics. 2020 Oct;19(10):1649-1663.
ID8agg cells
2.5 μM
72 h
Rabusertib induced DNA damage and increased PDL1 expression, while Cefepime significantly reduced PDL1 expression and induced γH2AX, indicating its ability to overcome PDL1 overexpression caused by DNA damage.
Int J Mol Sci. 2022 May 4;23(9):5129.
T24 cells
250 nM
96 h
To investigate the effects of Rabusertib on PDL1 expression in tumor cells and the combination effects with Cefepime. The results showed that Cefepime significantly reduced PDL1 overexpression induced by Rabusertib and enhanced its cytotoxic effects
Int J Mol Sci. 2022 May 4;23(9):5129.
ID8agg cells
80 μM
96 h
Cefepime strikingly improved the efficacy of the Chk1i rabusertib, indicating its ability to enhance sensitivity to DNA-damaging agents.
Int J Mol Sci. 2022 May 4;23(9):5129.
CRC-SCs
50 µM
72 h
To evaluate the effect of Rabusertib on cell proliferation and survival of CRC-SCs, the results showed that Rabusertib significantly affected the survival rate of CRC-SCs.
Cell Death Differ. 2021 Jul;28(7):2060-2082.
SW837
0.025 μM SN-38
72 h
To validate the combined effect of Rabusertib and SN-38, results showed that the combination effect is primarily mediated through CHEK1 inhibition.
Nature. 2022 Mar;603(7899):166-173.
SNU-81
0.025 μM SN-38
72 h
To validate the combined effect of Rabusertib and SN-38, results showed that the combination effect is primarily mediated through CHEK1 inhibition.
Nature. 2022 Mar;603(7899):166-173.
Rabusertib 动物实验
Species
Animal Model
Administration
Dosage
Frequency
Description
References
Mice
DLBCL xenograft model
Intraperitoneal injection
90 mg/kg
Twice a week, monitoring tumor growth
Evaluate the synergy of SUMOi and CHK1i
EMBO Mol Med. 2023 Sep 11;15(9):e16431
Mice
T24 cell xenograft model
Intraperitoneal injection
2.5 mg/kg
Daily, continuous treatment
Cefepime significantly improved the efficacy of rabusertib and prolonged mouse survival
Int J Mol Sci. 2022 May 4;23(9):5129.
Mice
NSG mice
Intraperitoneal injection
2.5 mg/kg
Once daily, until the end of the experiment
Cefepime significantly improved the efficacy of the Chk1i rabusertib, significantly prolonging the survival of mice.
Int J Mol Sci. 2022 May 4;23(9):5129.
NOD/SCID mice
Colon cancer xenograft model
Oral Rabusertib, intraperitoneal Irinotecan
200 mg/kg
Daily Rabusertib, twice weekly Irinotecan, for 24-35 days
To validate the combined effect of Rabusertib and Irinotecan, results showed that the combination therapy significantly inhibited tumor growth.
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