title: Combined haploinsufficiency for ATM and RAD9 as a factor in cell transformation, apoptosis, and DNA lesion repair dynamics.
abstract: Loss of function of oncogenes, tumor suppressor genes and DNA damage processing genes has been implicated in the development of many types of cancer, but for the vast majority of cases, there is no link to specific germ line mutations. In the last several years, heterozygosity leading to haploinsufficiency for proteins involved in DNA repair pathways was shown to play a role in genomic instability and carcinogenesis after DNA damage is induced. Because the effect of haploinsufficiency for one protein is relatively small, we hypothesize that predisposition to cancer could be a result of the additive effect of heterozygosity for two or more genes, critical for pathways that control DNA damage signaling, repair or apoptosis. To address this issue, primary mouse cells, haploinsufficient for one or two proteins, ATM and RAD9, related to the cellular response to DNA damage were examined. The results show that cells having low levels of both ATM and RAD9 proteins are more sensitive to transformation by radiation, have different DNA double-strand break repair dynamics and are less apoptotic when compared with wild-type controls or those cells haploinsufficient for only one of these proteins. Our conclusions are that under stress conditions, the efficiency and capacity for DNA repair mediated by the ATM/RAD9 cell signaling network depend on the abundance of both proteins and that, in general, DNA repair network efficiencies are genotype-dependent and can vary within a specific range.
authors.affiliation: Center for Radiological Research, College of Physicians and Surgeons, Columbia University, 630 West 168th Street, New York, NY 10032, USA. lbs5@columbia.edu
authors.forename: Lubomir B
authors.initials: LB
authors.lastname: Smilenov
authors.forename: Howard B
authors.initials: HB
authors.lastname: Lieberman
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Mitchell
authors.forename: Ronald A
authors.initials: RA
authors.lastname: Baker
authors.forename: Kevin M
authors.initials: KM
authors.lastname: Hopkins
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Hall
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics* / Q000528:radiation effects; D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins / Q000235:genetics*; D002471:Cell Transformation, Neoplastic / Q000235:genetics* / Q000528:radiation effects; D004249:DNA Damage; D004260:DNA Repair / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000172:deficiency / Q000235:genetics*; D005260:Female; D006239:Haplotypes; D051379:Mice; D018345:Mice, Knockout; D011247:Pregnancy; D017346:Protein Serine-Threonine Kinases / Q000172:deficiency / Q000235:genetics*; D013950:Thymus Gland / Q000166:cytology / Q000528:radiation effects; D025521:Tumor Suppressor Proteins / Q000172:deficiency / Q000235:genetics*
chemical_list: D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D025521:Tumor Suppressor Proteins; C069930:rad9 protein; D064007:Ataxia Telangiectasia Mutated Proteins; C576325:Atm protein, mouse; D017346:Protein Serine-Threonine Kinases