title: Defective double-strand DNA break repair and chromosomal translocations by MYC overexpression.
abstract: DNA repair mechanisms are essential for the maintenance of genomic integrity. Disruption of gene products responsible for DNA repair can result in chromosomal damage. Improperly repaired chromosomal damage can result in the loss of chromosomes or the generation of chromosomal deletions or translocations, which can lead to tumorigenesis. The MYC protooncogene is a transcription factor whose overexpression is frequently associated with human neoplasia. MYC has not been previously implicated in a role in DNA repair. Here we report that the overexpression of MYC disrupts the repair of double-strand DNA breaks, resulting in a several-magnitude increase in chromosomal breaks and translocations. We found that MYC inhibited the repair of gamma irradiation DNA breaks in normal human cells and blocked the repair of a single double-strand break engineered to occur in an immortal cell line. By spectral karyotypic analysis, we found that MYC even within one cell division cycle resulted in a several-magnitude increase in the frequency of chromosomal breaks and translocations in normal human cells. Hence, MYC overexpression may be a previously undescribed example of a dominant mutator that may fuel tumorigenesis by inducing chromosomal damage.
authors.affiliation: Department of Medicine, Division of Oncology, Stanford University, Stanford, CA 94305-5151, USA.
authors.forename: Asa
authors.initials: A
authors.lastname: Karlsson
authors.forename: Debabrita
authors.initials: D
authors.lastname: Deb-Basu
authors.forename: Athena
authors.initials: A
authors.lastname: Cherry
authors.forename: Stephanie
authors.initials: S
authors.lastname: Turner
authors.forename: James
authors.initials: J
authors.lastname: Ford
authors.forename: Dean W
authors.initials: DW
authors.lastname: Felsher
mesh_terms: D001483:Base Sequence; D002460:Cell Line; D019457:Chromosome Breakage; D004247:DNA / Q000235:genetics / Q000378:metabolism; D004260:DNA Repair / Q000235:genetics*; D005720:Gamma Rays; D015870:Gene Expression; D016259:Genes, myc; D006801:Humans; D007621:Karyotyping; D014178:Translocation, Genetic
chemical_list: D004247:DNA