Abrogation of Chk1-mediated S/G2 checkpoint by UCN-01 enhances ara-C-induced cytotoxicity in human colon cancer cells  

作　　者：Rong-guangSHAO Chun-XiaCAO YvesPOMMIER 

机构地区：[1]InstituteofMedicinalBiotechnology,ChineseAcademyofMedicalSciences,PekingUnionMedicalCollege,Beijing100050,China [2]LaboratoryofMolecularPharmacology,NCI／NIH,MD20892,USA

出　　处：《Acta Pharmacologica Sinica》2004年第6期756-762,共7页中国药理学报（英文版）

基　　金：Project supported by the grants of NIH and NFCR (USA); thegrant of NationalDistinguished Young Scholars(No 30025043);the National Special Research Program (No 2002AA2Z346D);and the State Key Basic R&D Programme "973" (No2002CB513108).2

摘　　要：AIM: To investigate whether 7-hydroxystaurosporine (UCN-01) affects cell cycle progression in arabinosylcytosine (ara-C) treatedhuman coloncarcinoma HT-29cells. METHODS:Cytotoxicity, DNA synthesis, cell cycle distribution, protein level, and kinase activity were determined by clonogenic assay, flow cytometry, DNA synthesis assay, immunoblotting, and kinase assays, respectively. RESULTS: UCN-01 abrogated an S/G2-phase checkpoint in HT- 29 cells treated with ara-C. When UCN-01 was added after treatment with ara-C, the rate of recovery of DNA synthesis was enhanced and colony-forming ability diminished. Thus, premature recovery of DNA synthesis was associated with increased cytotoxicity. Measurements of cyclin A and B protein levels, Cdk2 and Cdc2 kinase activities, Cdc25C phosphorylation, and Chk1 kinase activity were consistent with UCN-01-induced abrogation of the S/G2-phase checkpoint in ara-C treated cells. CONCLUSION: The abrogation of the S/G2 checkpoint may be due to inhibition of Chk1 kinase by UCN-01. The enhanced cytotoxicity produced when UCN-01 was combined with ara-C suggested a rationale for the use of this drug combination for tumors that might be susceptible to cell cycle checkpoint abrogation.AIM: To investigate whether 7-hydroxystaurosporine (UCN-01) affects cell cycle progression in arabinosylcytosine (ara-C) treatedhuman coloncarcinoma HT-29cells. METHODS:Cytotoxicity, DNA synthesis, cell cycle distribution, protein level, and kinase activity were determined by clonogenic assay, flow cytometry, DNA synthesis assay, immunoblotting, and kinase assays, respectively. RESULTS: UCN-01 abrogated an S/G2-phase checkpoint in HT- 29 cells treated with ara-C. When UCN-01 was added after treatment with ara-C, the rate of recovery of DNA synthesis was enhanced and colony-forming ability diminished. Thus, premature recovery of DNA synthesis was associated with increased cytotoxicity. Measurements of cyclin A and B protein levels, Cdk2 and Cdc2 kinase activities, Cdc25C phosphorylation, and Chk1 kinase activity were consistent with UCN-01-induced abrogation of the S/G2-phase checkpoint in ara-C treated cells. CONCLUSION: The abrogation of the S/G2 checkpoint may be due to inhibition of Chk1 kinase by UCN-01. The enhanced cytotoxicity produced when UCN-01 was combined with ara-C suggested a rationale for the use of this drug combination for tumors that might be susceptible to cell cycle checkpoint abrogation.

关 键 词：hydroxystaurosporine chk1 protein kinase DNA repair cell cycle 

分 类 号：R735.35[医药卫生—肿瘤]