title: Knockdown of Chk1 sensitizes human colon carcinoma HCT116 cells in a p53-dependent manner to lidamycin through abrogation of a G2/M checkpoint and induction of apoptosis.
abstract: Recent advances in cell cycle regulation have led to a suggestion of therapeutically targeting cell cycle checkpoint pathways in cancer cells to increase the toxicity of DNA-damaging agents. In this study, we investigate whether knockdowns of checkpoint kinases Chk1 and Chk2 by RNA interfering potentiate the cytotoxicity and abrogate G(2)/M checkpoint induced by DNA-damaging agent lidamycin (LDM) in HCT116 cells with different p53 status. Our results showed that Chk1 knockdown enhanced the cytotoxicity of LDM through abrogating G(2)/M arrest and increasing apoptosis to a greater extent in HCT116 p53(-/-) cells than in p53(wt) cells. Abrogation of LDM-induced G(2)/M arrest by Chk1 knockdown was associated with reducing the inactivated phosphorylations of Cdc25C and Cdc2. LDM-induced gamma-H2AX was increased in cells with Chk1 knockdown, indicating that DNA double-strand breaks (DSBs) were enhanced. Furthermore, knockdown of Chk1 also increased LDM-mediated apoptotic cell death in p53 knockout cells with activation of caspase-2 and caspase-3. On the contrary, knockdown of Chk2 had no impact on G(2)/M arrest or apoptosis induced by LDM. Moreover, dual knockdown of Chk1 and Chk2 failed to achieve better efficacy than Chk1 alone. Taken together, we suggest that Chk1 is a potential therapeutic target to sensitize human p53 deficient cancer cells to LDM.
authors.affiliation: Department of oncology, Institute of Medicinal Biotechnology, Peking Union Medical College, Chinese Academy of Medical Sciences, Beijing, China.
authors.forename: Yu
authors.initials: Y
authors.lastname: Pan
authors.forename: Kai-Huan
authors.initials: KH
authors.lastname: Ren
authors.forename: Hong-Wei
authors.initials: HW
authors.lastname: He
authors.forename: Rong-Guang
authors.initials: RG
authors.lastname: Shao
mesh_terms: D000617:Aminoglycosides / Q000494:pharmacology*; D000903:Antibiotics, Antineoplastic / Q000494:pharmacology*; D017209:Apoptosis / Q000235:genetics; D015153:Blotting, Western; D053143:Caspase 2 / Q000378:metabolism; D053148:Caspase 3 / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D002455:Cell Division / Q000187:drug effects / Q000235:genetics; D048708:Cell Growth Processes / Q000187:drug effects / Q000235:genetics; D000071877:Checkpoint Kinase 1; D064447:Checkpoint Kinase 2; D003110:Colonic Neoplasms / Q000188:drug therapy* / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D003546:Cysteine Endopeptidases / Q000378:metabolism; D053281:Enediynes / Q000494:pharmacology*; D016195:G2 Phase / Q000187:drug effects / Q000235:genetics; D055785:Gene Knockdown Techniques; D045325:HCT116 Cells; D006801:Humans; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011494:Protein Kinases / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000172:deficiency / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
chemical_list: D000617:Aminoglycosides; D000903:Antibiotics, Antineoplastic; D018797:Cell Cycle Proteins; D053281:Enediynes; D047428:Protein Kinase Inhibitors; D034741:RNA, Small Interfering; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; C058024:C 1027; D011494:Protein Kinases; D064447:Checkpoint Kinase 2; C000605867:CHEK1 protein, human; C578634:CHEK2 protein, human; D000071877:Checkpoint Kinase 1; D017346:Protein Serine-Threonine Kinases; C490360:CASP2 protein, human; D053143:Caspase 2; D053148:Caspase 3; D003546:Cysteine Endopeptidases