title: Sensitivity to DNA cross-linking chemotherapeutic agents in mismatch repair-defective cells in vitro and in xenografts.
abstract: Together with tolerance to killing induced by methylating agents, loss of mismatch repair (MMR) has previously been found to be associated with hypersensitivity to the DNAcross-linking agent 1-(2-chloroethyl)-3-cyclohexyl-nitrosourea(CCNU) in several human tumor cell lines (Aquilina et al., 1998). Here, we have investigated whether MMR might act as an efficient repair pathway and provide protection against the clastogenicity induced by CCNU and whether the hypersensitivity of MMR-defective cells is extended to other cross-linking agents. An increase in cell killing and in the frequency of micronuclei was observed after CCNU exposure in 2 hPMS2-defective clones (clones 6 and 7) compared with the parental HeLa cells. Introduction of a wild-type copy of chromosome 7 in clone 7 led to re-expression of the hPMS2 protein and brought survival and chromosomal damage upon CCNU exposure to parental levels. Our data indicate that MMR protects against the clastogenic damage induced by this drug. The hPMS2-defective HeLa cells were also hypersensitive to killing by mitomycin C. Mitomycin C sensitivity was confirmed in an hMLH1-defective clone derived from Raji cells and in msh2-defective mouse embryo fibroblasts derived from knock-out mice. hPMS2-defective and parental HeLa cells were transplanted into nude mice, and the animals were treated with mitomycin C. While parental cell growth rate was unaffected, the growth of MMR-defective tumor was significantly reduced. Our results indicate that the in vitro hypersensitivity to mitomycin C conferred by loss of MMR is paralleled in vivo and may have implications for the chemotherapy of MMR-defective tumors.
authors.affiliation: Laboratory of Comparative Toxicology and Ecotoxicology, Istituto Superiore di Sanità, Rome, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Fiumicino
authors.forename: S
authors.initials: S
authors.lastname: Martinelli
authors.forename: C
authors.initials: C
authors.lastname: Colussi
authors.forename: G
authors.initials: G
authors.lastname: Aquilina
authors.forename: C
authors.initials: C
authors.lastname: Leonetti
authors.forename: M
authors.initials: M
authors.lastname: Crescenzi
authors.forename: M
authors.initials: M
authors.lastname: Bignami
mesh_terms: D000251:Adenosine Triphosphatases; D000818:Animals; D020137:Base Pair Mismatch; D002051:Burkitt Lymphoma / Q000188:drug therapy / Q000473:pathology; D002455:Cell Division / Q000187:drug effects; D003432:Cross-Linking Reagents / Q000627:therapeutic use / Q000633:toxicity*; D045643:DNA Repair Enzymes; D004268:DNA-Binding Proteins; D006367:HeLa Cells; D006801:Humans; D008130:Lomustine / Q000627:therapeutic use / Q000633:toxicity*; D008558:Melphalan / Q000627:therapeutic use / Q000633:toxicity; D051379:Mice; D018345:Mice, Knockout; D008819:Mice, Nude; D015162:Micronucleus Tests; D000070976:Mismatch Repair Endonuclease PMS2; D016685:Mitomycin / Q000627:therapeutic use / Q000633:toxicity*; D051718:MutS Homolog 2 Protein; D011506:Proteins / Q000235:genetics*; D011518:Proto-Oncogene Proteins / Q000172:deficiency / Q000235:genetics; D014183:Transplantation, Heterologous; D014407:Tumor Cells, Cultured
chemical_list: D003432:Cross-Linking Reagents; D004268:DNA-Binding Proteins; D011506:Proteins; D011518:Proto-Oncogene Proteins; D016685:Mitomycin; D008130:Lomustine; D000251:Adenosine Triphosphatases; C094934:PMS2 protein, human; C499533:Pms2 protein, mouse; C497172:MSH2 protein, human; D000070976:Mismatch Repair Endonuclease PMS2; C497173:Msh2 protein, mouse; D051718:MutS Homolog 2 Protein; D045643:DNA Repair Enzymes; D008558:Melphalan