d15fdd5e-602d-4462-8484-a3cec84728f6
title
Functional consequences of  ATM  sequence variants for chromosomal radiosensitivity.
5547d3a2-56ad-4f48-b037-ab6b7d6872f1
abstract
The  ATM [for ataxia-telangiectasia (A-T) mutated]  protein plays a key role in the detection and cellular response to DNA double-strand breaks. Several single-nucleotide polymorphisms (SNPs) have been described in the  ATM  gene; however, their association with cancer risk or radiosensitivity remains to be fully established. In this study, the functional consequences of specific  ATM  SNPs on in vitro radiosensitivity, as assessed by micronuclei (MN) formation, were measured in lymphoblastoid cell lines established from 10 breast cancer (BC) patients carrying different  ATM  missense SNPs, six A-T patients, six A-T heterozygotes (A-T het), and six normal individuals. The BC, A-T het, and A-T cell line groups showed significantly higher mean levels of MN formation after exposure to ionizing radiation (IR) than did the group containing normal cell lines, with similar levels in the BC and A-T het groups. Within the BC lines studied, the group composed of the six carrying the linked  2572T>C (858F>L)  and  3161C>G (1054P>R)  variants had a higher level of MN after IR exposure compared to that observed in the remaining four BC or in the normal cell lines. This increase was not related to the constitutive  ATM  mRNA level, which was similar in these BC and the normal cell lines. Our results indicate that alterations in the  ATM  gene, including the presence of heterozygous mutations and the 2572C and 3161G variant alleles, are associated with increased in vitro chromosomal radiosensitivity, perhaps by interfering with  ATM  function in a dominant-negative manner.