Characterization of the breast cancer associated ATM 7271T>G (V2424G) mutation by gene expression profiling.
Mutations in ATM are responsible for the autosomal recessive disorder ataxia telangiectasia. Heterozygous mutations in ATM have been associated with an elevated risk of breast cancer. We previously reported one breast cancer family in which ATM 7271T>G (V2424G) segregated with disease, and apparently acted in a dominant negative manner. We now report the screening of 782 multiple-case breast cancer families that identified two additional index cases with ATM 7271T>G. Phylogenetic sequence analysis showed that V2424 is a highly conserved residue, and that the 2424G variant is likely to interfere with function. To elucidate the consequences of this mutation, we expression profiled wild-type, heterozygous, and homozygous lymphoblastoid cell lines (LCLs) from Scottish and Australian families using an oligonucleotide microarray. Cluster analysis revealed 77 genes that were differentially expressed in homozygous and heterozygous V2424G cells (compared to wild-type) and 11 genes differentially expressed in the homozygous cells. We also evaluated the profiles of LCLs after exposure to ionizing radiation (IR) and identified 77 genes that were differentially expressed in wild-type cells, but not in homozygous or heterozygous V2424G cells. We validated the expression differences by RT-PCR in additional heterozygous V2424G LCLs from another breast cancer family. We found no consistent cytotoxicity or abrogation of ATM kinase activity after IR in seven heterozygous V2424G LCLs, compared to wild-type LCLs, but did find an increase in the number of chromosomal aberrations. These data suggest that the V2424G missense mutation acts largely as a dominant negative in terms of the associated expression profiles.
Waddell
Nic
N
Queensland Institute of Medical Research, Brisbane, Queensland, Australia.
Jonnalagadda
Jyoti
J
Marsh
Anna
A
Grist
Scott
S
Jenkins
Mark
M
Hobson
Karen
K
Taylor
Malcolm
M
Lindeman
Geoff J
GJ
Tavtigian
Sean V
SV
Suthers
Graeme
G
Goldgar
David
D
Oefner
Peter J
PJ
Taylor
Darrin
D
Grimmond
Sean
S
Khanna
Kum Kum
KK
Chenevix-Trench
Georgia
G
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D064007:Ataxia Telangiectasia Mutated Proteins; D001943:Breast Neoplasms / Q000097:blood / Q000235:genetics*; D018797:Cell Cycle Proteins / Q000235:genetics*; D045744:Cell Line, Tumor; D017124:Conserved Sequence; D004268:DNA-Binding Proteins / Q000235:genetics*; D005091:Exons; D005190:Family; D020869:Gene Expression Profiling; D006801:Humans; D008969:Molecular Sequence Data; D020125:Mutation, Missense; D020411:Oligonucleotide Array Sequence Analysis; D019683:Penetrance; D010802:Phylogeny; D017346:Protein Serine-Threonine Kinases / Q000235:genetics*; D016415:Sequence Alignment; D025521:Tumor Suppressor Proteins / Q000235:genetics*
D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D025521:Tumor Suppressor Proteins; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases