title: Mismatch repair system decreases cell survival by stabilizing the tetraploid G1 arrest in response to SN-38.
abstract: The role of the mismatch repair (MMR) system in correcting base-base mismatches is well established; its involvement in the response to DNA double strand breaks, however, is less clear. We investigated the influence of the essential component of MMR, the hMLH1 protein, on the cellular response to DNA-double strand breaks induced by treatment with SN-38, the active metabolite of topoisomerase I inhibitor irinotecan, in a strictly isogenic cell system (p53(wt), hMLH1(+)/p53(wt), hMLH1(-)). By using hMLH1 expressing clones or cells transduced with the hMLH1-expressing adenovirus as well as siRNA technology, we show that in response to SN-38-induced DNA damage the MMR proficient (MMR(+)) cells make: (i) a stronger G2/M arrest, (ii) a subsequent longer tetraploid G1 arrest, (iii) a stronger activation of Chk1 and Chk2 kinases than the MMR deficient (MMR(-)) counterparts. Both Cdk2 and Cdk4 kinases contribute to the basal tetraploid G1 arrest in MMR(+) and MMR(-) cells. Although the Chk1 kinase is involved in the G2/M arrest, neither Chk1 nor Chk2 are involved in the enhancement of the tetraploid G1 arrest. The long-lasting tetraploid G1 arrest of MMR(+) cells is associated with their lower clonogenic survival after SN-38 treatment, the abrogation of the tetraploid G1 arrest resulted in their better clonogenic survival. These data show that the stabilization of the tetraploid G1 arrest in response to double strand breaks is a novel function of the MMR system that contributes to the lesser survival of MMR(+) cells.
authors.affiliation: Department of Gastroenterology, Charité, Campus Benjamin Franklin, Berlin, Germany.
authors.forename: Mandar Ramesh
authors.initials: MR
authors.lastname: Bhonde
authors.forename: Marie-Luise
authors.initials: ML
authors.lastname: Hanski
authors.forename: Jenny
authors.initials: J
authors.lastname: Stehr
authors.forename: Britta
authors.initials: B
authors.lastname: Jebautzke
authors.forename: Roser
authors.initials: R
authors.lastname: Peiró-Jordán
authors.forename: Henry
authors.initials: H
authors.lastname: Fechner
authors.forename: Kazunari Kazushige
authors.initials: KK
authors.lastname: Yokoyama
authors.forename: Weei-Chin
authors.initials: WC
authors.lastname: Lin
authors.forename: Martin
authors.initials: M
authors.lastname: Zeitz
authors.forename: Christoph
authors.initials: C
authors.lastname: Hanski
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D002166:Camptothecin / Q000031:analogs & derivatives* / Q000494:pharmacology; D002470:Cell Survival; D000071877:Checkpoint Kinase 1; D051357:Cyclin-Dependent Kinase 2 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D051358:Cyclin-Dependent Kinase 4 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D004249:DNA Damage / Q000187:drug effects; D053843:DNA Mismatch Repair / Q000187:drug effects; D016193:G1 Phase / Q000187:drug effects*; D006801:Humans; D000077146:Irinotecan; D000070957:MutL Protein Homolog 1; D009369:Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D009687:Nuclear Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D011003:Ploidies; D011494:Protein Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014407:Tumor Cells, Cultured; D014410:Tumor Stem Cell Assay; D016159:Tumor Suppressor Protein p53 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D000972:Antineoplastic Agents, Phytogenic; C501486:MLH1 protein, human; D009687:Nuclear Proteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D000077146:Irinotecan; D011494:Protein Kinases; C000605867:CHEK1 protein, human; D000071877:Checkpoint Kinase 1; C495894:CDK2 protein, human; C495900:CDK4 protein, human; D051357:Cyclin-Dependent Kinase 2; D051358:Cyclin-Dependent Kinase 4; D000070957:MutL Protein Homolog 1; D002166:Camptothecin