title: Single-cell analysis of loss of heterozygosity at the ATM gene locus in Hodgkin and Reed-Sternberg cells of Hodgkin's lymphoma: ATM loss of heterozygosity is a rare event.
abstract: Hodgkin's lymphoma (HL) is a lymphoid malignancy characterized by the presence of rare neoplastic cells, Hodgkin and Reed-Sternberg (HRS) cells, scattered among a predominant population of inflammatory cells. On the basis of previously reported cytogenetic analyses, the ATM (ataxia-telangiectasia mutated) gene at 11q22-23 has been implicated in the etiology of HL. We therefore developed a single-cell PCR approach to detect ATM loss of heterozygosity (LOH) in HRS cells. Three microsatellites were investigated; 1 localized inside the ATM gene and the remaining 2 in close proximity. In 2 of the 15 lymph node samples, an allelic loss of the ATM gene locus was detected. ATM protein expression was examined in 8 cases (including 1 of the 2 cases with LOH) by immunohistochemistry. In the case associated with an allelic loss, the ATM protein was absent in the HRS cells, whereas in the 7 remaining cases, without detectable LOH at the ATM locus, nuclear ATM expression was observed. In the 2 HL cases with LOH, the ATM gene was sequenced following whole genome amplification of DNA isolated from microdissected HRS cells. In 1 of these 2 cases, a splice site mutation in the second ATM allele was found. This mutation could generate a premature termination codon leading to a marked instability and a rapid degradation of the resulting ATM mRNA transcripts. This latter event could explain the loss of the expression of the ATM protein in HRS cells as detected by immunohistochemistry in this particular case. As previously reported in some B-cell lymphomas, our results suggest that ATM genetic anomalies could play a role in the pathogenesis of a subset of HL cases.
authors.affiliation: INSERM U563, CPTP, Oncogenèse et Signalisation dans les Cellules Hématopoïétiques et Plateau Technique d'Histopathologie Experimentale, IFR30, Purpan Hospital, 31059 Toulouse, France.
authors.forename: Virginie
authors.initials: V
authors.lastname: Lespinet
authors.forename: Fanny
authors.initials: F
authors.lastname: Terraz
authors.forename: Christian
authors.initials: C
authors.lastname: Recher
authors.forename: Elias
authors.initials: E
authors.lastname: Campo
authors.forename: Janet
authors.initials: J
authors.lastname: Hall
authors.forename: Georges
authors.initials: G
authors.lastname: Delsol
authors.forename: Talal
authors.initials: T
authors.lastname: Al Saati
mesh_terms: D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins / Q000235:genetics*; D043171:Chromosomal Instability; D004268:DNA-Binding Proteins / Q000235:genetics*; D020869:Gene Expression Profiling; D006689:Hodgkin Disease / Q000235:genetics* / Q000503:physiopathology; D006801:Humans; D007150:Immunohistochemistry; D019656:Loss of Heterozygosity; D017346:Protein Serine-Threonine Kinases / Q000235:genetics*; D012333:RNA, Messenger / Q000032:analysis; D016539:Reed-Sternberg Cells; D025521:Tumor Suppressor Proteins / Q000235:genetics*
chemical_list: D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D012333:RNA, Messenger; D025521:Tumor Suppressor Proteins; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases